v1.6 spec updates

- Remove “set as default” from action menu
- Sub-header on Sounds setting page is “Manage Sounds” instead of “My
Sounds”
- Creation via Manager - cancel goes back to manager instead of pick
activity
- Create screen - Untitled can be use for ringtone name if file name
and song name aren’t available
- default ringtone string updated
- Creating ringtones from other apps - banner confirmation replaced
with full screen dialogue
- Sub-headers for Ringtone Manager are “Custom Ringtones” and “Firefox
Ringtones”
- Added string for alerts to delete confirmation page