Let PLUS occur once anywhere in dial-str network portion.

Create a new extractNetworkPortion() function, since the old one is
public, that does effectively the same thing but is more flexible as
just mentioned.

Addresses issue:
http://buganizer/issue?id=2013998

Change-Id: Ie5df08ef9c871881e8728a44abf0385908000823
7 files changed