Refactorings
SPI impl is it's own class now
License header in DefaultMasterImplSPI
Merge branch '1.9-maint' into masterfix

Conflicts:
	enterprise/backup/src/main/java/org/neo4j/backup/OnlineBackupKernelExtension.java
	enterprise/ha/src/test/java/org/neo4j/ha/TestPullUpdatesApplied.java
Merge branch '1.9-maint' into masterfix
Merge branch '1.9-maint' into masterfix
Assign SPI. Duh.
Merge pull request #1368 from rickardoberg/masterfix

Refactoring of MasterImpl and BackupImpl to have SPI, so that they are testable