You can now specify a custom StateVertex factory.

The hashcode and equals in the StateVertex are used in the
StateFlowGraph that Crawljax uses. This means that using a custom DOM
comparator has no use, because in the back-end, the hashcode and equals
will determine the behaviour. This commit fixes that by allowing a user
to specify a custom StateVertex factory where you can create your own
StateVertexes with custom hashcode/equals methods.

Fixes #347
Merge pull request #369 from crawljax/fix/347-custom-comparator

You can now specify a custom StateVertex factory.
Merge pull request #380 from jhejderup/master

#372 'about:blank' URL causes a NPE
Version updates
Merge branch 'master' of github.com:crawljax/crawljax