document THUMBNAIL_PRESERVE_FORMAT
Merge pull request #196 from fusionbox/preserve_format

Document THUMBNAIL_PRESERVE_FORMAT setting
update hashes and urls
remove encoding for hash function
refactor logic that checks if file exists in the templatetag
use strings instead of unicode literals in log
add @skip to stalling tests
fix typo in test_quality
fix python 3 compatibility in tests
Revert "fix typo in test_quality"

This reverts commit 8ec8f263617e14ce733904de74de3de516a85749.
This issue seems to be only a problem on os x
add wand python package in travis settings
add libboost-thread-dev to apt dependencies in travis
fix nonascii test
fix travis config

* Fix typo
* Add redis service
add python 3 compatibility to hashing
make string check in template tag py3 compatible
use range instead of xrange

xrange is not present in python 3
make tests more python 3 compatible
make tests more python 3 compatible
made imagemagick python 3 compatible