Made options to go back to add page or view task.

Also, made end-date mandatory.
Added calendar date selectors for start/end dates.

Which are now adjustable! Two birds with one stone!
Merge remote-tracking branch 'origin/master' into improve_addpage

Conflicts:
	static/js/bootstrap-datepicker.js
	taskrabbit/templates/taskrabbit/base.html
Changed calendar to use new date names
cleaning up after git's mess once again

why does it do this
it's not even just me, it did this to Sam too
argh
Added checkbox to email someone about assignation.
Make it not freak out under a specific condition

i.e. if you check the 'email' box, and then set it to none, the email box is still checked, just invisible. So that case is now covered.
Merge pull request #6 from terabyte128/improve_addpage

Improvements to 'add task' page