generate version keywords

ICS product lists are usually pretty small, so we can simply generate a version key for each setup EUPS product. Chosing the git description if there are both a git and an eups version is simple, and gets us the following for an actively developed installation (for this ticket).

2019-07-02T22:47:33.699 xcu_b2 i version_ics_actorkeys="1.1.2-70-gf8dbe5a"
2019-07-02T22:47:33.700 xcu_b2 i version_ics_config="1.4.5"
2019-07-02T22:47:33.708 xcu_b2 i version_ics_launch="1.0.1"
2019-07-02T22:47:33.708 xcu_b2 i version_ics_xcuactor="1.10.4-dirty"
2019-07-02T22:47:33.709 xcu_b2 i version_ics_xcu_rtdadio="1.1.1-dirty"
2019-07-02T22:47:33.709 xcu_b2 i version_pfs_utils="1.0.2-3-g7e0c06f"
2019-07-02T22:47:33.710 xcu_b2 i version_tron_actorcore="2.0.3-1-gb077477"
2019-07-02T22:47:33.844 xcu_b2 i version="1.10.4-dirty"

This does require both git and the gitpython package. The second is available from conda. The first is a bit more trouble for the BEEs, since they do not have git-core installed, an in order to install that you need to run apt update to get new repo addresses, etc. If git is not available, the EUPS tags are returned, or "unknown".