[Closes jadell/neo4jphp#97] Adding specific properties to serialize for node and relation classes
Fix to make the test work on lower php versions
Forgot the ";"
Ignoring PhpStorm project settings
Adding/updating documentation
Fixing labels in the node tests since they're not strings but  objects
Adding `__sleep`, `setClient` and `getClient` on `Label` to handle serialization
Setting the `client` in a `PropertyContainer` will also update the clients of its dependent objects if they're not yet set
Merge branch 'master' of https://github.com/huafu/neo4jphp into huafu-master
Fix some spacing and robustify some tests.