Generate a callsite identifier associated with each callsite

Generate a unique string name for a callsite that appears in every node
Address coding standards
Merge branch 'master' of https://github.com/DynamoDS/Dynamo into newMaster
Addressed code review comments on callsite cache
Add testcase for callsite reuse on changing the argument variable
Merge pull request #1779 from junmendoza/newMaster

Generate a callsite identifier associated with each callsite