barclamp_uninstall.rb: Add --debug, --rpm and --help flags

Right now, --rpm doesn't change any behavior, but having this flag to be
consistent with barclamp_install.rb makes sense.
Merge pull request #1814 from vuntz/barclamp_uninstall_rpm

https://github.com/crowbar/crowbar/pull/1814

Merged by devtool for cloudsleuth