[1/3] Base: Increasing ringtone volume

Ascending ringtone volume at configurable intervals and starting volume.

Settings: https://gerrit.omnirom.org/#/c/4885/
Telephony: https://gerrit.omnirom.org/#/c/4887/

Change-Id: I36df10d56612f67c5d44efd9c4e31532de06d901