prototype for a unified load function for all file types
switch to using class_exts instead of hardcoded list. Raise an error if we can't find a loader
break line in exception, fix typos
Add handler switching based on class_exts to pims.open

add some basic tests of pims.open
Add ffmpeg crud from tests to gitignore
address concerns raised in pr thread
Merge pull request #74 from tdimiduk/master

ENH : first-draft of unified auto-dispatching open function.

prototype for a unified load function for all file types