Added lock file for serial device
Merge branch 'master' into rvw

Conflicts:
	sgw/sgw.c
Cleaned up serial lock at appropriate return points
updated lock file privilages
Merge branch 'master' of https://github.com/ska-sa/katcp_devel into sgw-lock
Fixed segmentation fault on certain instances of lock file creation and deletion
Merge pull request #6 from ska-sa/sgw-lock

Sgw lock