Moved jackson dependency to gremlin-server.
Introduce gremlin-server plugins.
Add deps operation to list all dependencies initialized by grape.
Got rid of GraphFactory by pushing open() to Graph interface.
Add tests for Compare.
Bring GraphFactory back and make Graph API expose open().

Enforce open() override with tests.  Enforce private constructors for Graph implementations.
added author notes and fixed parameterization on DefaultQuery.
removed unnecessary test() method in DefaultQuery and removed unused imports in Graph.
moved GraphFactory to util/
moved GraphFactory to util/
moved GraphFactory to util/
fixed directory structure for blueprints-test.
minor naming and finalization tweaks to GraphFactory
Make Graph.open() take an Optional<Configuration>.

Those implementations that have a default construction that doesn't require a Configuration object can do Graph.open(Optional.empty()).
added property exceptions to ExceptionFactory.
generic typing has character that is the character of the type.
GraphFactory.open() can't have a null for the Configuration argument.

It minimally requires that argument to determine which graph to instantiate.
Merge remote-tracking branch 'origin/master'
renamed generic variables in TinkerGraph.
Pass Optional<Configuration> from GraphFactory.