Added test for slave-only instance being elected coordinator
Fixes so that slave-only instances not only try not to win elections, but actively don't switch to master in the case they are coordinators (e.g. because the instance created the cluster)

Conflicts:
	enterprise/ha/src/main/java/org/neo4j/kernel/ha/HighlyAvailableGraphDatabase.java
	enterprise/ha/src/test/java/org/neo4j/ha/TestSlaveOnlyCluster.java
Fixed merge issues
Merge pull request #2341 from rickardoberg/slaveonlyfix2

Slave-only instances no longer becomes master