Ring Lockscreen: add a zoom effect for secondary rings

Added a zoom effect when middle ring is dragged over secondary ring.
Also had side-effect of decreasing sensitivity of secondary rings.

Perhaps this can combined with http://review.cyanogenmod.com/#change,8294
for more visual feedback as well...

Change-Id: Ia5a0330ac9db46b09b71638cfdf5c1e3926976a6