Refactor and clean the newly introduced code

* Use better method names, clean up the internal API.
* Call save_model from the parent when finished.

It is a good practice to always call the original method from
the overriden one, unless you have a very good reason not to.
This way it allows others to do their extensions as well.
Merge pull request #16 from knaperek/master

Cleanup of the new code
Show/hide transition buttons according to permission

Instead of displaying all buttons and check if the user is allowed to
make the transition, first checks whether the user has permission and
then displays or hides the button. Transitions without permission
configured are not affected.
need to use the template processor
django.core.context_processors.request, put in
TEMPLATE_CONTEXT_PROCESSORS
Fixed a mistake

Fixed missing request param
Merge pull request #18 from mord4z/master

Show/hide transition buttons according to permission
Increase required django-fsm version
Increase release version