closes #39

• adds support for the --profile, only accepts string wrapped ints or will scream.
• combines each threads slowest into 1 total i.e if 3 threads you will be served the slowest 10 not 30
• added specs to try and test this

Questions:

• i had a hard time actually building the required struct for the profile formatter as unlike the others it uses the provided params as objects instead of just being a string like i.e dump_summary
• i couldn't actually workout a nice place to get the list of example groups from so atm it will just get all unique file locations and and descriptions based on count of how many gorups
• i cant seem to get the exception of raising of the argument error?

@ilyazub i had a crack i know this is close, but it does feel like ive hacked it a bit open to any feedback!