CallTracker: Add delay to reduce cpu load

A delay is introduced to avoid rapid repeated polling which leads to
high cpu usage and spamming of the modem and logcat.

Change-Id: I6eb12babb723b5f5164ef43493c971f607746484
Merge branch 'cm-10.1.1' into martincz
Merge remote-tracking branch 'mokee/jb-mr1_mkt' into HEAD