Merge dev branch into master

[jefft0]

Now that we have closed issue OpenPTrack/open_ptrack_v2#73 to merge the open_ptrack_v2 dev branch into master, we need to do the same here. Since the dev branch diverged from master on January 17, 2019, there are 54 commits, mostly by @itabr in January and February.

[jefft0]

There is one especially large commit: 0e653b4

This adds many new files. Are they all necessary?

[jburkeucla]

Closing this as it has been merged.

[jburkeucla]

Closed incorrectly

[jefft0]

Before we merge dev into master, we should probably remove this backup file:
https://github.com/OpenPTrack/open_ptrack_docker_config/blob/dev/setup_host_backup