Replace mutable default parameters
Simplify chained comparison
Fix spelling mistakes
Fix PEP 8 coding style violations
Remove redundant parentheses
Fix instance attribute defined outside __init__
Fix single-quoted docstring
Small CSS fixes
Tweak .gitignore to ignore more coverage files
Minor cleanup of Python client
Add metadata extractor plugin
Add test to ensure access control on download endpoints
Fix downloads in the web client

The authentication change broke them.
Get uploads actually working in phantomjs environment

This was tougher than it sounds.
Unbreak other test
Add a test for downloading behavior

It's mocked since phantom chokes on hard redirects
Merge pull request #334 from girder/fix-web-client-downloads

Fix web client downloads
Added a rest method to copy an item.  Added the abaility to copy a file to the file model.  Adjusted the gridFS and S3 assetstores so that duplicated files don't need to duplicate data.
Added tests for copying items and for some other cases that were not covered.  Fixed an issue in testing for blank metadata keys.  When downloading a multi-file item, I've added a sort parameter so that the files are in a predicatable order.
Fixed a python style complaint.