Repo generation: log and keep going on error

* Delete old report() functions, use logging instead
* Skip addons which have problems (but give a warning)

tests/test_blenderpack.py

@@ -2,6 +2,7 @@
 
 import unittest
 import os.path
+import json
 import blenderpack
 
 class test_blenderpack_make_repo(unittest.TestCase):