Merge pull request #9 from mcallistersean/master

Use native json module if available
Endpoint: ignore request body for GET or DELETE requests

Also extract the body parser into separate function for better
realibility.
Endpoint: move authentication check into separate method

To make the code more readable
add http.HttpError exception to make it easier to raise HTTP errors

This is very useful in cases where a low-level method wants to
interrupt the request flow and directly return the (usually error)
response to the user.
add restless.modelviews: generic CRUD views for models
add tests for restless.modelviews
add documentation for modelviews
update docs' RST syntax
linter fixes
modelviews: use modelform_factory instead of doing it by hand
add modelviews.ActionEndpoint
refactor modelviews and add better docs

Changes to the modelviews include:

* URL keyword argument is 'pk' by default and can be overridden
* DetailEndpoint has only get_instance; get_query_set removed
* misc fixes
tests: silence intentional warnings
updated copyright and made the authors list explicit
improve docs
modelviews: rename 'pk_url_kwarg' to 'lookup_field'

Cleaner and in sync with the future Django naming.
python3 support
fix Python 2.6 compatibility
docs: advertise Python 2.6, 2.7 and 3.3 support
Travis: simplify install requirements so that test runs are faster