Adding the foundation for classifying TTLs into bins

https://gist.github.com/lakshmi-kannan/cfa272facce11c9dd26f
https://gist.github.com/tilogaat/44a4006f1750b4c92ecf

Based on the above gists, we want the ability to classify TTLs in separate bins. This PR adds code to ConfigTTLProvider to provide the infrastructure for binning. This infrastructure will be used by Ingestion and Rollups to bin the TTLs

2 points I'd like to get feedback about - 
* Check to see if the class TTLBins is in the appropriate place 
*  Check to see if the test adequately covers most of the cases 
possible NullPointerException here if `getConfigTTLForUserTTL()` returns null, which it can.