categories filtering
create exercise view
fix for creating exercises
predefined exercises goes first
post review fixes
Merge branch 'exercises-list' into 68610518-new-exercise

Conflicts:
	app/controllers/exercises.js
exercise creation fix
jshint violations fixes
ipmroved categories binding
Merge pull request #3 from ComputerScienceStudents/68610518-new-exercise

68610518 new exercise