Trap AssertionError to quash unsightly traceback

Fix this in 1.0.0
No longer seeing the traceback from #168

Fixes #168
Merge pull request #177 from huit/bugfix/175-cloudlet_update_breakage_workaround

Trap AssertionError to quash unsightly traceback
Merge pull request #178 from huit/bugfix/169-vagrantfile_in_working_directory

Unable to replicate Vagrant/Jinja template interaction bug
Merge remote-tracking branch 'upstream/master'