Change getMessageScopes parameter type

Tracking an upstream change in TP3's VertexProgram interface
Tracking TP3 changes for InputFormats

This commit follows Marko's recent repackaging of giraph-gremlin into
hadoop-gremlin.  This commit deletes GiraphInputFormat and
GiraphVertexInputFormat.  The logic in these classes is now in
hadoop-gremlin.  Titan just needs to provide an
InputFormat<NullWritable, VertexWritable> that reads vertices from
Titan and produces VertexWritable (a thin wrapper around TinkerVertex
right now).  This has simplified things on the Titan side.

I tested the Cassandra IF and BulkLoader against TP 3.0.0-SNAPSHOT at
commit 7a79fc1b531d2871dffcaf241de712bbfb116efe.