SERVER-14668 Remove 'experimental doc locking legacy code'

o Cleans up references to the experimental doc locking code.
o Removes the 'old' lock manager.
o Moves the 'new' lock manager out of the 'newlm' namespace.
SERVER-15262 Lock manager fixes and unit-tests

o Timeout of a lock upgrade throws an assertion error
o Add better tracing to the LockManager dump method
o Move LockHead inside lock_mgr_new.cpp, since it is not needed outside