master: Calculate chunks' checksum

To ensure metadata integrity when delegating dump to metarestore,
chunks' checksum is checked.

Change-Id: I4343ff740208141dc5d8f965444119d789c4ee4a
master: Calculate xattrs' checksums

To ensure metadata integrity when delegating dump to metarestore,
xattrs' checksum is checked.

Change-Id: Id4e347af40b3bf316e5d0f2597bd9791709f5bba
mount: Disable support for capability-based security

Kernel on some Linux distributions issues getxattr("security.capability")
request every 64 kB of written data. This is a big problem for the master
server if we want to write a lot of data. This commit fixes this issue in
the most simple way by returning ENOTSUP when trying to use capabilities on
files. In the future we may consider implementing some cache for these calls
or a configuration option which will allow users to decide what to do with
capabilities.

Change-Id: I850d1cd59147eb8b2d9510e0e4df6f16282c0bb8
master: Fix bug in fs_repair

When mfsfilerepair'ing a valid file, file's ctime and mtime was updated,
but shouldn't have been. This commit fixes it and also corrects
test_metadata_dump.

Change-Id: Ie7bcb5cac2b7c96d91b72398a39d388507a5c4b8