Merge pull request #338 from untitaker/sprint-branch

Sprint branch
Add default to string_join; make efficient
Fix test_form_data_ordering
appiter produces bytes
Make string_join accept iterables
Remove unused import
Fix UnboundLocalError in string_join
Fix generate_etag
Fix test_etag_response_mixin_freezing
Make FileWrapper iterable
Fix test_shared_data_middleware test case
Eliminate ResourceWarnings on 3.x
Use __rdiv__ implementation for __truediv__ on 3.x
Fix test_dynamic_charset_response_mixin
Make _fs_transaction_suffix bytes
Pass bytes to sha1 in sessions.generate_key
Use unicode paths on 3.x
Remove 3.2 from travis
Don't send emails travis
A bunch of the easy fixes