packaging: update dependencies

This patch updates both the packaging files and the dockerfiles to
remove unused dependencies and add dependencies which can be installed
from the system instead of being built from contrib.

- remove libsrtp
- add jsoncpp
- add libupnp
- add libav related packages for Ubuntu 16.04, since it's recent enough
  to use the packaged version

Change-Id: I5b3432f15582c3f8170a580a8e783bec33a98c05
Tuleap: #823