Handle pruning old format logs, Fixes #2265
Merge pull request #2343 from jakewins/1.9-prune-oldlogs

Handle pruning old format logs, Fixes #2265
Merge branch '1.9-maint' into 2.0-merge-1.9

Conflicts:
	community/kernel/src/main/java/org/neo4j/kernel/impl/transaction/xaframework/LogPruneStrategies.java
Merge branch '2.0-merge-1.9' into 2.1-merge-2.0-2
Merge pull request #2355 from chrisvest/2.1-merge-2.0-2

2.1 merge 2.0 again