Improved performance of OrientGraph.getVertices() and getEdges() when no index is configured.

Now it execute a query rather than browsing all the items and filtering
in memory. With remote protocol this was unacceptable.
Made PropertyGraphSail configurable such that edges may either be viewed as first-class objects (with one edge per id, type, label, head, and tail) or as single statements
Added a saveRDF method to SaiGraph, to complement loadRDF
added a test to ensure proper behavior around updating a vertex's property.
Minor: removed all the compilation warnings
Merge branch 'master' of git://github.com/tinkerpop/blueprints
OrientDB: warning if tx is automatically committed when create new type or an index
Merge remote-tracking branch 'origin/master' into graphfactory