Added package envs command for printing tree of environments

Closes #5

PACKAGE.md

@@ -148,6 +148,21 @@ username
   /staging: admin
 ```
 
+You can also just show the hierarchy of environments and sub-environments by running:
+```bash
+configstore package envs
+```
+This returns an output very similar to that of `configstore package tree`:
+```bash
+/dev
+  /aws
+    /server1
+    /server2
+  /local
+/live
+/staging
+```
+
 To process templates in the context of a given environment, you can run:
 ```bash
 configstore package process_templates dev/local /path/to/output

cmd/configstore/main.go

@@ -436,6 +436,19 @@ func main() {
 					},
 					BashComplete: PackageCmdAutocomplete(nil),
 				},
+				{
+					Name:      "envs",
+					Usage:     "Print out a hierarchical structure of all environments and sub-environments",
+					Action:    cmdPackageEnvs,
+					Flags: []cli.Flag{
+						cli.StringFlag{
+							Name:  "basedir",
+							Usage: "The base directory for the configuration package structure",
+							Value: "./config",
+						},
+					},
+					BashComplete: PackageCmdAutocomplete(nil),
+				},
 				{
 					Name:   "diff",
 					Usage:  "Prints out the differences between two environments",

cmd/configstore/package-envs.go

@@ -0,0 +1,38 @@
+package main
+
+import (
+	"fmt"
+	"gopkg.in/urfave/cli.v1"
+	"strings"
+)
+
+func cmdPackageEnvs(c *cli.Context) error {
+	basedir := c.String("basedir")
+	return printDirs(basedir + "/env", 0)
+}
+
+func printDirs(basedir string, indent int) error {
+	dirs, err := ListDirs(basedir)
+	if err != nil {
+		return fmt.Errorf("%w; Failed to list top-level directories at: %s", err, basedir)
+	}
+
+	for _, dir := range dirs {
+		out := ""
+		if indent == 0 {
+			out = formatGreen(dir)
+		} else if indent == 1 {
+			out = formatCyan(dir)
+		} else {
+			out = dir
+		}
+
+		fmt.Println(strings.Repeat(" ", indent * 2) + "/" + out)
+
+		if err := printDirs(basedir + "/" + dir, indent + 1); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}

configstore.bats

@@ -195,7 +195,7 @@
   rm -rf test_data/out_test
 }
 
-@test "configstore package ls, tree, diff" {
+@test "configstore package ls, envs, tree, diff" {
   rm -rf test_data/package_test
   rm -rf test_data/out_test
   mkdir test_data/out_test
@@ -219,6 +219,9 @@
   run bin/darwin/amd64/configstore package ls --basedir test_data/package_test dev/local
   [ "$status" -eq 0 ]
 
+  run bin/darwin/amd64/configstore package envs --basedir test_data/package_test
+  [ "$status" -eq 0 ]
+
   run bin/darwin/amd64/configstore package tree --basedir test_data/package_test
   [ "$status" -eq 0 ]