Issue #26 Detach trimmer layout from controller

Image trimmer controller now has no access to the layout. All communication
is done by events.

Image trimmer module now creates a region that manages the appearance of the
image trimmer layout.
Issue #26 Slider handles over dragging

When the trimmer slider is dragged out of bounds, adjust its width to
the largest possible amount.
Merge branch 'image_trimmer'

Conflicts:
	app/assets/javascripts/kiwi/components/image_trimmer/image_trimmer.js.coffee
	app/assets/javascripts/kiwi/components/image_trimmer/image_trimmer_view.js.coffee
	app/assets/javascripts/kiwi/views/event_form.js.coffee
Issue #26 Calculate slider factor based on width

The slider factor needs to account for the fact that the slider will never
reach the end of the track. Only expected the slider to reach its own width
proximity from the end of the track.
Issue #26 Keep image in frame during resize

While the image is being resized, keep it within the boundaries of the frame.
Issue #26 Detect if image is too small

If the image is too small to work with, do not allow it to be resized by scroll.
Merge branch 'master' into time-picker

Conflicts:
	app/assets/javascripts/kiwi/views/event_form.js.coffee