Merge pull request #43 from plukevdh/master

Make 'os' a non-dev only gem.
Made localhost:7474 the default server url

Can now create a session with Neo4j::Session.open(:server_db)
Support for Schema Constraints closes #44
Release 3.0.0.alpha.8
Add support for regex query conditions
Updated README with example for conditions with regexp search
release 3.0.0.alpha.9
Added failing test for andreasronge/neo4j#319

update_props must handle nil values
Fix for #46, update_props with nil values

 Does need some refactoring and maybe some unit tests
drop nil values on create