Fixed broken integration tests.

Interestingly this amounted to renaming the sum() method in sample.groovy to addItUp().  Not sure why that is, because sum() has been fine for the last five months.  Not clear why this is suddenly broken.  I can only think that somehow groovy is hanging on to some other reference to sum() in a cache somewhere, but that seems unlikely too given the tests we have to prevent such things....mysterious.
Remove todo comment.
Flip back on GraphMigrator tests now that a custom kryo instance can be specified.
Moved strategy methods around to make them a little easier to follow.
Add javadoc to GraphStrategy.
Add strategy methods for Property/VertexProperty value() #346
Add strategy methods for VertexProperty/Property.key() #346
Make the MapReduce related Tinker-classes public so other implementations can use them since they are not related to TinkerGraph.
Merge branch 'master' of https://github.com/tinkerpop/tinkerpop3
Minor test method renaming.
Add tests to enforce StrategyWrapped on Graph instances. #346
Add constructor allowing assignment of Strategy implementation in StrategyWrappedGraph.
Fixed test case which made the implicit assumption that the graph supports user assigned ids.
Merge branch 'master' of https://github.com/tinkerpop/tinkerpop3