Test joining an IBSS (AdHoc) network

Add infrastructure to site_linux_router for "IBSS" class servers.
Create "IBSS" mode for site_wlan_connect.py

BUG=chromium-os:12042
TEST=Run test

Change-Id: If8de20485f799888561067e0db5b4e97c9c7b04d

Review URL: http://codereview.chromium.org/6603026
4 files changed