proper env modifiers support

This implements proper modifier support in the env file using this new fork of the godotenv library. The modifier implementation is quite basic for but can be improved later if needed. See this commit for the actual implementation.

Because we are now using proper modifer parsing, it does not affect the parsing of value, so this is possible again:
```
MY_VAR="#foo"
```
Closes coop-cloud/organising#535

cli/app/new.go

@@ -97,7 +97,7 @@ var appNewCommand = cli.Command{
 		var secrets AppSecrets
 		var secretTable *jsontable.JSONTable
 		if internal.Secrets {
-			sampleEnv, err := recipe.SampleEnv(config.ReadEnvOptions{})
+			sampleEnv, err := recipe.SampleEnv()
 			if err != nil {
 				logrus.Fatal(err)
 			}
@@ -168,7 +168,7 @@ var appNewCommand = cli.Command{
 type AppSecrets map[string]string
 
 // createSecrets creates all secrets for a new app.
-func createSecrets(cl *dockerClient.Client, secretsConfig map[string]string, sanitisedAppName string) (AppSecrets, error) {
+func createSecrets(cl *dockerClient.Client, secretsConfig map[string]secret.SecretValue, sanitisedAppName string) (AppSecrets, error) {
 	// NOTE(d1): trim to match app.StackName() implementation
 	if len(sanitisedAppName) > 45 {
 		logrus.Debugf("trimming %s to %s to avoid runtime limits", sanitisedAppName, sanitisedAppName[:45])
@@ -217,7 +217,7 @@ func ensureDomainFlag(recipe recipe.Recipe, server string) error {
 }
 
 // promptForSecrets asks if we should generate secrets for a new app.
-func promptForSecrets(recipeName string, secretsConfig map[string]string) error {
+func promptForSecrets(recipeName string, secretsConfig map[string]secret.SecretValue) error {
 	if len(secretsConfig) == 0 {
 		logrus.Debugf("%s has no secrets to generate, skipping...", recipeName)
 		return nil

cli/app/secret.go

@@ -20,19 +20,23 @@ import (
 	"github.com/urfave/cli"
 )
 
-var allSecrets bool
-var allSecretsFlag = &cli.BoolFlag{
-	Name:        "all, a",
-	Destination: &allSecrets,
-	Usage:       "Generate all secrets",
-}
+var (
+	allSecrets     bool
+	allSecretsFlag = &cli.BoolFlag{
+		Name:        "all, a",
+		Destination: &allSecrets,
+		Usage:       "Generate all secrets",
+	}
+)
 
-var rmAllSecrets bool
-var rmAllSecretsFlag = &cli.BoolFlag{
-	Name:        "all, a",
-	Destination: &rmAllSecrets,
-	Usage:       "Remove all secrets",
-}
+var (
+	rmAllSecrets     bool
+	rmAllSecretsFlag = &cli.BoolFlag{
+		Name:        "all, a",
+		Destination: &rmAllSecrets,
+		Usage:       "Remove all secrets",
+	}
+)
 
 var appSecretGenerateCommand = cli.Command{
 	Name:      "generate",
@@ -87,28 +91,22 @@ var appSecretGenerateCommand = cli.Command{
 			logrus.Fatal(err)
 		}
 
-		secretsConfig, err := secret.ReadSecretsConfig(app.Path, composeFiles, app.Recipe)
+		secrets, err := secret.ReadSecretsConfig(app.Path, composeFiles, app.Recipe)
 		if err != nil {
 			logrus.Fatal(err)
 		}
 
-		secretsToCreate := make(map[string]string)
-		if allSecrets {
-			secretsToCreate = secretsConfig
-		} else {
+		if !allSecrets {
 			secretName := c.Args().Get(1)
 			secretVersion := c.Args().Get(2)
-			matches := false
-			for name := range secretsConfig {
-				if secretName == name {
-					secretsToCreate[name] = secretVersion
-					matches = true
-				}
-			}
-
-			if !matches {
+			s, ok := secrets[secretName]
+			if !ok {
 				logrus.Fatalf("%s doesn't exist in the env config?", secretName)
 			}
+			s.Version = secretVersion
+			secrets = map[string]secret.SecretValue{
+				secretName: s,
+			}
 		}
 
 		cl, err := client.New(app.Server)
@@ -116,7 +114,7 @@ var appSecretGenerateCommand = cli.Command{
 			logrus.Fatal(err)
 		}
 
-		secretVals, err := secret.GenerateSecrets(cl, secretsToCreate, app.StackName(), app.Server)
+		secretVals, err := secret.GenerateSecrets(cl, secrets, app.StackName(), app.Server)
 		if err != nil {
 			logrus.Fatal(err)
 		}
@@ -276,7 +274,7 @@ Example:
 			logrus.Fatal(err)
 		}
 
-		secretsConfig, err := secret.ReadSecretsConfig(app.Path, composeFiles, app.Recipe)
+		secrets, err := secret.ReadSecretsConfig(app.Path, composeFiles, app.Recipe)
 		if err != nil {
 			logrus.Fatal(err)
 		}
@@ -311,12 +309,7 @@ Example:
 
 		match := false
 		secretToRm := c.Args().Get(1)
-		for secretName, secretValue := range secretsConfig {
-			val, err := secret.ParseSecretValue(secretValue)
-			if err != nil {
-				logrus.Fatal(err)
-			}
-
+		for secretName, val := range secrets {
 			secretRemoteName := fmt.Sprintf("%s_%s_%s", app.StackName(), secretName, val.Version)
 			if _, ok := remoteSecretNames[secretRemoteName]; ok {
 				if secretToRm != "" {