ENH : ImageSequence can take in a list as input

Any input that is not a string is assumed to list-like
FIX: ImageSequence __repr__ shows '(list of images)'
TST: ImageSequence accepts a list of filenames.
TST : add extra meta-data for new tests
TST : removed redundant tests
TST : fix failing test
Merge pull request #78 from tacaswell/file_paths

ENH : ImageSequence accepts a list of filenames.