Merge develop into sqlalchemy

Here is the merge.  I tried to copy the new tests you added in develop to corresponding sql tests.  There were three of these in post_sql.py that I gave up on and just commented out: test_post_alternative_payload, test_post_dependency_fields_with_default, test_post_readonly_field_with_default.

All of the tests pass on Python 3.4.  The sql tests look like copies of the mongo tests, but the test code is all duplicated.  For some reason, the sql tests use a different schema.  To combine the two sets of tests into one, the sql test schema would have to match the mongo schema.  I guess this is more work for a later date...

I wouldn't expect a requirements.txt file in a library like this.  Also wouldn't expect == requirements on the install_requires in your setup.py.  This prevents users of the library from using later versions.  For example, you have 'flask==0.10.1' as a requirement.  When you push this to pypi, and somebody uses it months later, it prevents them from using flask 0.11 when it comes out.  Unless you know the code won't work with later versions, requiring a minimum version with 'flask>=0.10.1' establishes what this project needs but still lets it coexist with code requiring a later version.  All that said, I'll leave it to your better judgement what to do.

Let me know if I messed up the git stuff or the pull request...