AG: CLCC response can contain non-ATD characters

Test case:
1. Connect Plantronics backbeat PRO headset.
2. Initiate outgoing call from phone.
3. Accept the call from remote side and terminate call.
4. Try to redial from headset and observe

Failure:
AG is sending error for redial request from BT headset.

Root cause:
Sometimes, the number in CLCC response has "-".
Repeated from the headset, the ATD string has "-"
which is not allowed in the dial string for ATD and
errors.

Fix:
 * Sanitize CLCC response to only include valid ATD characters.
 * Accept "-" in ATD because it works for us.

Change-Id: I854165c7da295f428852c829543eb4fc18455d91