Split repo generation functionality out of blenderpack.py

Moved repo.json generation to make_repo.py
Package/addon parsing is getting a bit messy, this can be
cleaned up when we have a clearer idea of what a package is.

For now just make it work.

tests/test_helpers/addons/dir_invalid_addon/__init__.py

@@ -0,0 +1,12 @@
+bl_info = {
+    "author": "testscreenings, PKHG, TrumanBlending",
+    "version": (0, 1, 2),
+    "blender": (2, 59, 0),
+    "location": "View3D > Add > Curve",
+    "description": "Adds generated ivy to a mesh object starting "
+                   "at the 3D cursor",
+    "warning": "",
+    "wiki_url": "https://wiki.blender.org/index.php/Extensions:2.6/Py/"
+                "Scripts/Curve/Ivy_Gen",
+    "category": "Add Curve",
+}