Add error backtrace to safe_run output
Merge pull request #1 from jgoldschrafe/f-error-backtrace

Add error backtrace to safe_run output
[filters] added filters extension category
[filters] added options hash to run()
[filters] added category test and options tests
[filters] safe_run() error class and backtrace, thank you @jgoldschrafe!
[filters] codeclimate gem doesn't work w/ ruby 1.8