TinkerPop 3.0.0M4.

This is a major change to update this package to use TinkerPop 3.
TinkerPop 3 is not backwards compatible to TinkerPop 2. Many changes
are made in this commit to make unit tests pass, but more changes
should be made to clean up the result. For example, the fundamental
concept of a 'pipeline' in TP2 changed to a 'traversal' in TP3,
but this revision still uses the term Pipeline extensively in the
code.
Update README.md, and rename getProperty(key) -> value(key).

While updating the README.md to reflect that this revision is now TinkerPop3 compatible,
I noticed that the examples in the README used some APIs that changed with TP3, but had
not yet been fully converted in the source, i.e. our wrapper still used TP2 names. Those
have been fixed here, though there are definitely other such cases not yet changed.
Merge pull request #10 from jimlloyd/feature/port-to-tinkerpop3-rebase-v0.4.0-squashed

Port to TinkerPop3