Enhanced testing and building.

Run bioblend tests as part of Travis build process.
Fix Makefile target for building server variant of the container, add container target for spinning up a test container based on that.
Configure the GIE proxy and add a test for that starting up properly.
General improvements to /usr/bin/check-planemo-machine.sh tests.
Abandon Linuxbrew for installing planemo - I couldn't get it to work and we are moving toward Conda anyway.

galaxyproject / planemo-machine