Roaming blacklist

Rename isSameOperatorConsideredRoaming to isOperatorConsideredRoaming.
Have isOperatorConsideredRoaming take precedence over isOperatorConsideredNonRoaming.
This makes it easier to blacklist specific networks that lie within a
whitelist range (eg, whitelist all carriers under 310xxx except 310410).

Bug: 17684236
Change-Id: I2275cd3375e810a0a17ff28bf518e4ff5420cc14