Provide correct instuctions on how to use a proxy

The instructions result in a console warning, which can be removed
by using 'del' after declaring the proxy.
httplib2 v0.7 and above include SocksiPy

Change-Id: Ib92fb5e1d0ca135d529566b7f4ea225d648acac7
Merge "Provide correct instuctions on how to use a proxy"