Fix index conflict issue with 1.9

py2neo no longer raises exception on index conflict
Check for unsupported neo4j versions
Update changelog and versions etc
Alter version check
Prevent __bool__ operations on py2neo nodes

Evaluting if self.__node__ in 1.6 causes a cypher query to be executed
obviously we want to avoid this.
Fix for issue 79

- nice error message on incorrect relationship property
Keep 'self' representing current node in cypher

- for backwards compatability
Revert "Wrapping/unwrapping Record namedtuple"

This reverts commit 66028876269a18a4729eefc3222e1cb83a274d8b.
Cypher now backwards compatible with old versions
Merge branch 'master' of https://github.com/robinedwards/neomodel into feature_neo4j_20

Conflicts:
	neomodel/core.py