get vagrant version from last column of vagrant -v

previous versions of vagrant output verison in this format:
(master) ~/code/try-lipstick$ vagrant -v
Vagrant version 1.2.3

newer versions output as:
(master) ~/code/try-lipstick$ vagrant -v
Vagrant 1.3.1
Merge pull request #5 from jeffmagnusson/get_vagrant_version_fix

get vagrant version from last column of vagrant -v