Merge remote-tracking branch 'origin/1.9-maint'

Contains only:
000185d903db89fc651dd0df77c766b9fbb4eb9a: Fixes problem with parser not being thread safe
d3da2c164fd1c8d22e3a5d499c4775dad85bdb28: added status endpoint to indicate ability to process transactions, additional to the existing master/ slave endpoints
44c3e320330ecd71b687268c35ea7b436b553fbb: Cope with version check of very short store files.
e9d762bacf0d3d5c355069e25efdff09d2d68c29: Gets rid of even some more null handling for FileLock
0a5eb2aba58c9caf5061d88d20818157011a9add: Completes the change where FileLock throws IOException or returns an instance, i.e. stops using null for failure signal