Bug 537757 - Convert BackupStore to java.nio.file

- Cleanup to the path conversion methods
- Cleaned up the backup store root handling
- Using UUID for the unique part of the backup dir name
- Convert to Java 7 file API using only File.move()
  for the most critical operation.
- Improved logging
- Changed BackupStore to SimpleBackupStore
- Fixed the backup tests to use Java 7

Signed-off-by: Todor Boev <rinsvind@gmail.com>
Change-Id: I16f3496bf9accacdb2932b0a2a14a96d3581d37b
Reviewed-on: https://git.eclipse.org/r/c/equinox/rt.equinox.p2/+/182585
Tested-by: Equinox Bot <equinox-bot@eclipse.org>
14 files changed