Ignore ruby*/gems and venv/*
Update Ruby test suites

Testing on Ruby 1.8 is no longer a good idea: 1.8 is no longer
supported in any way, including security patches, so it will be
removed from recent OS distributions fairly soon and fewer
and fewer projects will be compatible with it.

Ruby clients run tests against 1.8.7 on travis-ci.org
and will do so for as long as it is available.
Ignore rubygems archives
Fix gems installation in make test