modem: Add set_madison_config command.

Add a command to set the contents of /var/cache/cromo/madison-config-group.
This lets users toggle between the old and new Verizon portals.

BUG=chromium-os:21589
TEST=Adhoc, sets the file

Change-Id: I1450ca9450d1ee0139e91a981e4f5925a202ca45
Reviewed-on: http://gerrit.chromium.org/gerrit/10044
Reviewed-by: Jason Glasgow <jglasgow@chromium.org>
Tested-by: ttuttle <ttuttle@chromium.org>
Commit-Ready: ttuttle <ttuttle@chromium.org>
1 file changed