API parameter "createTime" is now used by the join url.

refs #722
Fixed things related to the createTime parameter.

refs #722
Merge branch '722-use-parameter-create-time' of git://github.com/gmiotto/bigbluebutton_rails into gmiotto-722-use-parameter-create-time

Conflicts:
	app/models/bigbluebutton_room.rb
	lib/generators/bigbluebutton_rails/templates/migration.rb
	lib/generators/bigbluebutton_rails/templates/migration_2_0_0.rb
	spec/models/bigbluebutton_room_spec.rb
Merge PR #16 from gmiotto/722-use-parameter-create-time
Store BigbluebuttonRoom#create_time as decimal(14,0), not string

Best format found to store a number and still not lose millisecond precision.

refs #722