Issue #134 Remove /var/lib/alternatives/#{cmd} before calling alternatives.

This seems to fix the problem that we are seeing where jar does not get properly linked.
What we were seeing is the same as described here

http://johnglotzer.blogspot.com/2012/09/alternatives-install-gets-stuck-failed.html
Issue #134 - Adding tests to catch unlinked jar command
Merge pull request #144 from RallySoftware-cookbooks/Issue-134

Issue #134 Remove /var/lib/alternatives/#{cmd} before calling alternatives.