Disable VT features in Dialer,

+ Should be contingent on a setting in any case. In teh future this
will be derived from capability, but for the moment this feature
just won't be supported.
+ Pointed everything to a false flag in DialerUtils.

Bug: 16211386
Change-Id: I37e027c94e3411d8e73a349b3101fdb6ad598b3b