Change lava-master-image-scripts repo reference from launchapd to git.
Change lava-master-image-scripts repo reference from launchapd to git.

Change-Id: I3523077676c02b2732dc52764028421d5d0e736a

Linaro/lava-server,Linaro/lava-server,Linaro/lava-server,Linaro/lava-server