Create keyframe model to encapsulate general Skrollr logic, and subclass to start/target/end keyframes to create defaults for Flms-style animations.  Add supporting tests and migrations.  Build out UI for new/edit of image layers with keyframe attributes.
Remove debugger from gemfile; remove scroll_start initializer values in target and end keyframe models.
Remove slide stuff from keyframe model.
Use ||= instead of unless ... in build_default_keyframes
Fix indentation in image_layers_controller_spec
Minor formatting and variable name cleanups in tests
Add missing newline
Merge branch 'master' into layer_keyframes to fix merge conflicts.

Conflicts:
	app/models/flms/keyframe.rb
	app/views/flms/image_layers/_form.html.haml
	spec/controllers/image_layers_controller_spec.rb
	spec/features/layers/image_layers/edit_spec.rb
	spec/models/keyframe_spec.rb
	spec/models/start_state_keyframe_spec.rb
Merge pull request #11 from dhawt/layer_keyframes

Create keyframe model to encapsulate general Skrollr logic