Merge pull request #1 from HangfireIO/master

Pull in other's changes
Added GetDescription method to Cron

Added GetDescription method to Cron and 40 unit tests covering both old
and new functionality of Cron
Typo in readme.txt
Merge pull request #212 from keesschollaart81/patch-1

Typo in readme.txt
Merge pull request #210 from djrineh/master

Added GetDescription method to Cron.