Add version commmand

All packages installed with brew have the version of the package in the
name of the parent folder. Whereas those installed from source have the
git tags present.

With that in mind, either the git tags or parent folder name is referenced to
print the release version used.

Relates: #159

src/Whippet.php

@@ -28,6 +28,7 @@ public function commands()
         $this->command('migrate OLDPATH NEWPATH', 'Examines an existing wp-content directory and attempts to create an identical Whippet application.');
         $this->command('dependencies SUBCOMMAND', 'Manage dependencies (themes, plugins)');
         $this->command('deps SUBCOMMAND', 'Alias for dependencies');
+        $this->command('version', 'Prints whippet version');
     }
 
     public function plugins($plugin_command)
@@ -84,4 +85,18 @@ public function deps()
     {
         $this->dependencies();
     }
+
+    public function version()
+    {
+        $whippetPath = dirname(__DIR__);
+        $installedWithBrew = strpos($whippetPath, 'opt/homebrew');
+
+        if ($installedWithBrew) {
+            $whippetVersion = basename($whippetPath);
+        } else {
+            $whippetVersion = substr(`git --git-dir $whippetPath/.git describe --tags`, 1, 5);
+        }
+
+        echo $whippetVersion . "\n";
+    }
 };