gmerge: prefer server over local, don't pass -n to emerge
gmerge: prefer server over local, don't pass -n to emerge

Change-Id: I9ad398d13a4935fef3b075269e88ecbad125c5df

BUG=gmerge -n becomes emerge -n so it doesn't merge if already exists
TEST=verified proper operation with and without -n

Review URL: http://codereview.chromium.org/3402024

mgireesh05/dev-util,marineam/coreos-dev-util,coreos/dev-util,mgireesh05/dev-util,marineam/coreos-dev-util,coreos/dev-util,mgireesh05/dev-util,coreos/dev-util