Update to MapDB 0.9.10

Related to jankotek/blueprints/issues/5, I needed to see if the last MapDB 0.9.10 version solved the issue so I did the update myself (this PR). This seems to have solved the issue but it still needs deeper testing to be sure.

The details of the commits:
* 73baf47 to ddf0d20 Commits from upstream [tinkerpop/blueprints](https://github.com/tinkerpop/blueprints), fetch it to make these commits disappear from this PR
* e82151c Merge remote-tracking branch 'upstream/master'
* 67fb9d2 Update to MapDB 0.9.10 and make things compile
* a9b0865 Fix EdgeTestSuite#testGetEdgesByLabel (labels should be indexed in some way to honor supportsEdgeIteration=true)

All tests are passing using `mvn clean install -pl blueprints-core,blueprints-test,blueprints-mapdb-graph`.

Please note that this may need some improvements since I didn't get all the subtleties of the API yet. For instance, the hint provided by the method `Serializer#fixedSize`.