Make Neo4j::Session.current thread-safe

[cheerfulstoic]

I think that this would be pretty easy. See: http://stackoverflow.com/questions/34233349/reconnect-neo4jrb-connections-after-puma-fork-with-preload-app/34281962#34281962

[cheerfulstoic]

Done (at least I hope so)

[cheerfulstoic]

Not done ;( I think if a thread is made the session from the original thread should be used. Don't have time to look at the moment, so I reverted my other commit

[brucek]

In my initial tests, moving to Typhoeus (#272) seems to have solved my issues with puma and preload_app! as well.

[cheerfulstoic]

Nice! I actually was doing some stuff with the parallel gem ad threads and so I should try this (if we don't make it the default) the next time I do thread stuff