fix activerel bug and gemfile for travis
Merge pull request #418 from subvertallchris/classname_bug

fix activerel classname bug and travis error
Linked list support in has_many #416

First spike. We need some kind of callbacks when nodes are deleted so that the linked list can still be intact.
Started changing association and query_proxy, support has_many #416

 The question is if we should try to use cypher or if we should use the Neo4j::Node.node/rel/nodes/rels methods. I think the latter is easier but will not be as efficient on the Neo4j Server because of the many request it requires.

 Or we use this solution http://docs.neo4j.org/chunked/stable/cypherdoc-linked-lists.html
 Can it be done without the root node so that we don't have to create it for empty lists.