Add supported URI scheme to PhoneAccounts. (2/4)

Modify PhoneAccountRegistrar to load/save supported URI schemes to
the state XML file.
Added version check to state XML file and migration step to add
'sip' for SIPConnectionService PhoneAccounts, and 'tel' for all other
PhoneAccounts.

Bug: 17140110
Change-Id: Ic5d41254bade421cc39eb197a1d6fc2d6695f62f