Handle 400 Bad Requests w/ JSON API Error format
Add status code to error representation
Flatten 400 errors
Convert to JSON Patch-like error format
Handle 403 errors
'make coverage' works w/ pytest-cov
Refactor code and tests

JsonApiMixin now has these (better documented) methods:
- render - Decides which wrap method to use, renders response
- wrap_default - Wrapper for 'good' responses
- wrap_error - Wraps in JSON API Error format, configured by params
- wrap_bad_request - Configure wrap_error for 400 Bad Requests
- wrap_generic_error - Configure wrap_error for other errors

Added "succeeded in creating resource" tests to test_list.py
Moved "failed to create resource" tests to test_errors.py
Render parser errors differently than field errors
Fix parser error detection in py3
Merge pull request #3 from jwhitlock/bad_request

Handle 400 Bad Request w/ JSON API Error format
Preparing to work on the parser
Add basic support for links when parsing
Added support for M2M in links
Switch creation test to use links
Fixed README formatting