Add basic composer.json file.

composer.json

@@ -0,0 +1,7 @@
+{
+    "name": "_s",
+    "description": "Hi. I'm a starter theme called '_s', or 'underscores', if you like. I'm a theme meant for hacking so don't use me as a parent theme. Instead try turning me into the next, most awesome, WordPress theme out there. That's what I'm here for.",
+    "type": "wordpress-theme",
+    "license": "GPL-2.0 or later",
+    "version": "1.0.0"
+}