added Textare for comments in booking
migration file for adding a field for comments
Merge remote-tracking branch 'origin/dev' into 25-additional_information

Conflicts:
	models/Booking.php
Related to story #25.
Added dynamic width of the comments field. It is now also shown, when viewing a booking.
Related to story #25.
Migration for comments field added.
Merge remote-tracking branch 'origin/dev' into dev

Conflicts:
	models/Booking.php
#25 - inserted rules for comment field in a new line