LU-1406 ofd: OFD module framework

LU-1406 ofd: OFD module framework

The very basic functionality, obd_device plus lu_device,
no methods so far. Can be built and run but do nothing.

For ability to use OFD the test-framework check shell variable
USE_OFD and loads ofd.ko instead of obdfilter

Signed-off-by: Mikhail Pershin <tappro@whamcloud.com>
Change-Id: I2797f375aec63204eca9d435cf837636e84e09bd
Reviewed-on: http://review.whamcloud.com/2792
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Alex Zhuravlev <bzzz@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>