Use webp in path only when webp is supported
Add path format version to file result storages

Test Plan:
make test
Pass log level through upstart script
Creating directory before attempting to create file for detection.

Error solved:

IOError: [Errno 2] No such file or directory: '/var/tmp/thumbor/storage/ba/4ed3bf706f2efff35373ae03b52f850bd3a695.detectors.txt.e666f83dd1f94f96925b79f9ee272ebe'
Added tilde (~) to the encoded URL chars. Fixes #289.
Release 4.0.1
Merge pull request #288 from cicerocomp/error_mixed_storage

Creating directory before attempting to create file for detection.
Merge pull request #286 from mattrobenolt/master

Pass log level through upstart script
Updated tornado to the latest version. Fixes #272.
Merge pull request #253 from frankdu/webp_fix

Use webp in path only when webp is supported
Release 4.0.2
Trying to fix the the build with WebP mux
installing webp from source
proper download URL
compiling from source
return to proper folder
Hacking on thumbor? Here's how
Update CONTRIBUTING
LICENSE file
Small optimizations for convolution filter