[Bug Fix] Ignore exceptions about files not existing by using 'force' option on 'rm'
[Bug Fix] Avoid getting 'Infinity' or 'NaN' when dividing by 0.0
[Gemspec] Upgrade xcodeproj dependency to match new cocoapods verison's.
[Spec] Add test for divide by zero issue.
[Travis] Remove ruby 2.1.1 because it's broken on Travis.
Merge pull request #27 from venmo/marklarr/safe_remove_files

Safely remove files