LatinIME: Add setting to obey system haptic feedback setting

Use case: when I'm talking on the phone, the vibrator apparently makes
terrible noises for the other person.  This change lets me make the
keyboard obey a Tasker profile that disables haptic feedback during
calls.

Change-Id: I0c560c13d4bb083b9ba8bec7170275db4c3571c3