Fixed column height for small screens.
User can drag only his own tasks or tasks from shared stages.
Merge remote-tracking branch 'origin/master'

Conflicts:
	Symfony/src/DreamTeam/BoardBundle/Resources/views/Board/view.html.twig
Updated task stage change validation for programmer and tester
Fixed task stage change validators. Allowing to take any task from queue, done and tested stages.
Merge branch 'master'
Programmers and testers can now view personal boards and switch back to full board view
Added missing validation for number of tasks in "in-progress" stage.