- changed name convention in cobd, thus all MD related methods have _md_ prefix like...

- changed name convention in cobd, thus all MD related methods have _md_ prefix like cobd_md_getstatus(),
all data layer related have _dt_prefix and common one like cobd_connect() have no prefix at all.

- added hack to mdc_intent_lock() and cobd_md_intent_lock() to distinguish cobd case in mdc_intent_lock() and do not raise -ESTALE if obtained lock is not coherent wiht store id due to generation after switchin to cache cobd. This is dirty hack of course, but it should be for a while to pass cmobd/cobd related tests and Peter agreed it ok for now.