chef-client gem install does not honor .gemrc in time,
so specify the http-proxy option explicitly.
moreover, post-apt-config kickstart file has a syntax
error, which is also fixed in the patch.
Change-Id: Iadf78b6c0aff691e3f6824c20e906b75b681e848
Closes-bug: #1393967
Closes-bug: #1396948
a375b37153