Feature/writeboost test ruby log replay

[writeboost] add complex ruby compile test
Test scenario:
1. create a writeboost device with writeback disabled
2. expand a Ruby archive on the device
3. remove the device
4. recreate the device. The logs on the cache replayed
5. write back all the caches on the cache device
6. build and make test Ruby on the device
7. unmount and remove the device

----

This test is not clean. Actually, I found writeboost type 1 fails with xfs_repair that runs at the last (or second) unmount. Although build and make test Ruby succeeded xfs_repair somehow fails. This problem doesn't occur with type 0. So I think something added with type 1 doesn't work but seems to be working.

----

In case of using ext4 instead of xfs, the test passed. Isn't this a xfs issue?