OPENDJ-1449 : File-based changelog should handle partially written record left over from a previous failure
CR-3768

[Merge r10816 for Nicolas Capponi]
[Note: real merge of all changelog.file package content to be done in one shot in
 a future commit]

* LogFile.java
** Add a check of file validity in constructor when log file is write-enabled
** Recover the file if it is corrupted (partially written record) by truncating it

* BlockLogReader.java
** Add method checkLogIsValid() to check validity of file
 
* replication.properties
** Add new messages related to check and recovery

* LogFileTest.java
** Add tests for recovery after log file corruption

* Minor changes in other files