skeleton: filter out non-library packages

\Composer\InstalledVersions::getAllRawData() will return all composer
packages installed, regardless of their type. This caused a problem
when creating a "skeleton" project using composer. Currently, all
skeleton composer packages are of type "library" anyway so it's safe
to filter out the rest.

lib/Skeleton/Core/Skeleton.php

@@ -71,7 +71,8 @@ public static function get_all() {
 				}
 
 				list($vendor, $name) = explode('/', $package);
-				if ($vendor != 'tigron') {
+
+				if ($vendor !== 'tigron' || $details['type'] !== 'library') {
 					continue;
 				}
 
@@ -84,9 +85,10 @@ public static function get_all() {
 
 				$skeletons[] = $skeleton;
 			}
+
 			self::$skeleton_cache = $skeletons;
 		}
+
 		return self::$skeleton_cache;
 	}
-
 }