Phone: correct summary of national roaming [translation]

According to Android's writing guidelines for checkbox
settings [1], the summary should not reflect the state
of the checkbox setting but should describe the action
itself.

A workaround was applied earlier on, but this completely
removes the extra summary.

[1] http://developer.android.com/design/patterns/settings.html#writing

Change-Id: Ie2f6df479576d571d6402daa998e808f47e3aaaf

Conflicts:
	res/values-cs/cm_strings.xml
Phone: Update Afrikaans translation

Change-Id: If9015b356460b887280ecd535372d93c21ae9fa8
phone: Enable the blacklist by default

Change-Id: I0b2d3482d75abe9c9fc161f199782f27b9baa46b