Features generated can clobber

[SkepticRaven]

In a JABS project folder, cached features use the filename of the video.
This is fine because JABS projects require all videos and poses to be in the same folder.

However, when caching features through either classify.py's optional argument (to save cached features to a directory) or a standalone (currently in a dev branch https://github.com/KumarLabJax/JABS-behavior-classifier/tree/standalone-generate-features), they are not required to be in the same folder.
These approaches will clobber the cached features.

Proposed solution:
url-ify the cached features and enable hash checking of pose file used for generating (to enable dropping folders when trying to match)

[gbeane]

will likely change the cached features to use <file name>_<pose hash>.h5