Fix Swift process kill

stop_swift() was not killing all swift processes properly.  Change to
manually clean up all screen services with pkill.

Closes-bug: 1268794
Change-Id: Ibb7a2e0dd10a313609f05963264087f82f6f00e2
Merge branch 'code-cleanup' into dt-test
Merge branch 'enabled-base' into dt-test