Modified IntIndex to use BigInteger
Added tests for index values
Changed IntIndex to use BigInteger instead of int for #105

* Implemented IntIndex using BigInteger
* Updated unit tests to provide data validation
* Fixed some sneaky tabs that made it into the codebase.
* Updated Newtonsoft.Json and protobuf.NET to most recent version
Small addition to the release notes
Merge branch 'feature/gh-105' into develop