BLD : actually install the extern folder

 - minor PEP8
 - add pims.extern to the package list
FIX: Bug in loading TiffStack into API.
Merge pull request #72 from danielballan/fix-api-bug

FIX: Bug in loading TiffStack into API.
fix example notebook a bit so that it works with current pims
Merge pull request #73 from triplepoint217/master

fix example notebook a bit so that it works with current pims
BUG : made Frame respect creation time metadata

Frame(data, frame_no=frame_no, metadata=md_dict) dropped
md_dict.

 - Added test
 - minor style changes
Merge pull request #76 from danielballan/fix-metadata

TST/FIX: Implement metadata in Frame and add test
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 #69 from tacaswell/install_extern

BLD : actually install the extern folder
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
Update README.md

Typo
Merge pull request #81 from sciunto/patch-1

Update README.md
line 163, os is not defined
MNT: Added .pyd and .idea/ to .gitignore
Merge pull request #85 from ericdill/gitignore

MNT: Added .pyd and .idea/ to .gitignore