Some more cleanup, making it a bit easier to set up.

We now check if we can run coverage, we auto-set the project path from tc_all,
and we have some more bugs filed. There still is one path that each developer
will need to edit and set in the ./rbt wrapper script.

new file:   ../scripts/is_coverage_installed
new file:   Gemfile.lock
modified:   actions.rb
modified:   rbt.rb
modified:   tc_all
modified:   tc_all.rb