Abstracted transient locking methods and added unit tests for transient locks and the $force param (#195)
Merged tests for transient helper from 945e1da9443f375395f6664d37d14eaa208a500a with those in master (see #195)
Moved URL-specific functions into their own helper class; re-linked functions as necessary
Moved letterbox functions into TimberImageHelper, wrote some fun tests
Wrote tests to confirm letterbox functionality
removed some junk and added test for transparent image