Ambition open source project - datetime_helpers

Micah, Josh, Jared M, Jared L, Jeff, Travis, Wes O, Erik, please give this a good look over.

This PR contains a datetime_helpers package and a README documenting all of the public functions. It has 100% test coverage and circle integration.

I look forward to everyone's suggestions about this package. I'm not sure what else I might be leaving out, other than installation instructions and an author list. Any ideas on how to make this better are welcome.