Too generic install

[jskarpe]

Running with Beaker-librarian against Ubuntu 14.04 results in:

 [exec] ubuntu-1404 14:40:22$  apt-get install --force-yes  -y rubygems  
 [exec] Reading package lists...
 [exec] Building dependency tree...
 [exec] Reading state information...
 [exec] Package rubygems is not available, but is referred to by another package.
 [exec] This may mean that the package is missing, has been obsoleted, or
 [exec] is only available from another source
 [exec] However the following packages replace it:
 [exec]   ruby
 [exec] 
 [exec] E: Package 'rubygems' has no installation candidate
 [exec] 
 [exec] ubuntu-1404 executed in 2.52 seconds
 [exec] Exited: 100

You should leave the install of ruby to the nodeset instead