Merge pull request #369 from BrynCooke/master

Change Element.getProperty and Element.removeProperty to avoid casting in client code.
updated CHANGELOG and removed an old commented out test case.
Made line separators for graphml out os independent.
test cases around auto-typing introduced into Element.getProperty() and Element.removeProperty(). Removed some old commented out test cases in KeyIndexableGraph. Added more test cases to QueryTestSuite.
stricter Element property key/value testing. Only change, NULL no longer supported in GraphSON.
stricter Element property key/value testing. Only change, NULL no longer supported in GraphSON.
Renamed GraphSail's default-namespace property to _defaultNamespace, for consistency with other hidden properties
Revert "Renamed GraphSail's default-namespace property to _defaultNamespace, for consistency with other hidden properties"

This reverts commit 8450318db69401260dc17f38a4b34031dc4b742d.
Generalized IdGraph to selectively enable custom vertex or edge IDs, accommodating base graphs which do not support either edge or vertex indexing
Fixed failing test for RexsterGraph given Query changes.

Fixing this forced a change in Rexster as support of NULL on the query string was not allowed.
Merge remote-tracking branch 'origin/master'
updated JavaDoc on Vertex.
updated JavaDoc on Vertex.
Filled out JavaDoc for IdGraph
Null checks in transaction commit for OrientDB.
Merge remote-tracking branch 'origin/master'
2.3.0 release commit.
master branch is now 2.4.0-SNAPSHOT.
added MockSequalizable.equals(). Updated Query with Query.has(key,compare,value). The equivalent of Query.has(key,value,compare) has been deprecated.
Fixed #377 -- PropertyFilteredIterable is no longer a type requirement. Cherry picked to 2.4.0-SNAPSHOT.