Bumped version to 2.6.0-SNAPSHOT
Removed old repository elements
Added the hasImplicitElements feature for use with SailGraph and others which return elements not explicitly created with addVertex or addEdge
Bugfix blueprints-test use of convertId

The GraphTest convertId() and convertLabel() methods were
not being used in several places in the test suites.

Also convertId() was erroneously used instead of
convertLabel() in some other places.