Checks if tslint is available before calling it
Fixes #2 - Can't convert 'NoneType' object to str implicitly
Merge pull request #5 from theblacksmith/tslint-check

Checks if tslint is available before calling it
Merge pull request #6 from theblacksmith/fix-issue-2

Fixes #2 - Can't convert 'NoneType' object to str implicitly