Removed a mutable default param in Serializer.serialize().

I haven't seen this pop up explicitly as a bug in code; only noticed it
through code inspection.
Raise ApiFieldError on invalid datetimes
Thanks to RevSys & the PSF for funding a significant portion of the port!
Removed commercial support that's long since no longer been offered.
Probably breaking Travis. Again.
More Travis/tox fixes.
Maybe Travis will build now.
Reduce ApiKey key length to 128 (closes #757)

This avoids issues with MySQL where multi-byte encodings will cause a
256-character field to exceed the maximum index length (767 bytes).

https://github.com/toastdriven/django-tastypie/issues/757
Test fixes for Py3, Django changes

* tests:
    * use skipIf for digest, oauth tests to avoid Py3 failures
* tox:
    * split py2/py3 python-digest releases
    * Created tox deps-py2 / deps-py3 variables for each env to include
    * Moved python3-digest and oauth2 from requirements.txt to appropriate deps
    * Remove python 2.6 / django-dev target
* Remove remaining deprecated django.utils.simplejson usage
* Fix docs build
Tox: remove py26-dev, add py33-dev
Travis: avoid duplicate builds

Change .travis.yml to generate a build matrix which is only
TRAVIS_PYTHON_VERSION x DJANGO_VERSION, reducing the number of builds
from 15 to 5.
Update the SimpleCache implementation and docs to be up-to-date with Django 1.3+.
Fixed a bug where ``tastypie.utils.timezone.now`` could toss an exception. Thanks to tunix for the original patch!
Travis, you are fragile & sometimes I don't like you very much.
adds some notes on how to deal with throttling for a resourse
adds missing `:`
adds double `` for markdown
#273: Changes from llonchj; Added tests to cover dots in pks in urls.
Fixed #486 - Added documentation for disabling all methods on list and detail endpoints

Signed-off-by: Pankaj Singh <psjinx@gmail.com>
fix missing python-mimeparse dependency in setup.py