LU-6894 kernel: new kernel RHEL6.7 [2.6.32-573.3.1.el6]

LU-6894 kernel: new kernel RHEL6.7 [2.6.32-573.3.1.el6]

Add target and config files for new kernel in RHEL 6.7
Revise lbuild to add RHEL 6.7
Add new ldiskfs patch series for RHEL 6.7,
similar to 6.6 but without the
ext4-drop-inode-from-orphan-list-if-ext4_delete_inode-fails.patch
That change is now already present in the 6.7 version of ext4.

Test-Parameters: mdsdistro=el6.7 ossdistro=el6.7 \
  clientdistro=el6.7 mdsfilesystemtype=ldiskfs \
  mdtfilesystemtype=ldiskfs ostfilesystemtype=ldiskfs \
  testgroup=review-ldiskfs

Signed-off-by: Bob Glossman <bob.glossman@intel.com>
Change-Id: I09496b03b030fc678422a8d027ee185b8a660611
Reviewed-on: http://review.whamcloud.com/15701
Tested-by: Jenkins
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Yang Sheng <yang.sheng@intel.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>