Allow parallel_emerge to be used when network is unavailable.
Allow parallel_emerge to be used when network is unavailable.

When --getbinpkg is not used, skip looking on the remote server for
packages. This should allow people to use parallel_emerge with no
binary packages when the network is unavailable.

BUG=chromium-os:6684
TEST=Disconnect network and run ./build_packages --nousepkg

Change-Id: Id0e5d03aca30d85cb6990d977983f1e0655726ab

Review URL: http://codereview.chromium.org/3294022

coreos/scripts,fivethreeo/scripts,trnubo/scripts,vmware/coreos-scripts,bcwaldon/coreos-scripts,endocode/scripts,smilart/scripts,glevand/coreos--scripts,zhang0137/scripts,fivethreeo/scripts,trnubo/scripts,smilart/scripts,andrejro/coreos--scripts,BugRoger/scripts,gtank/scripts,smilart/scripts,fivethreeo/scripts,andrejro/coreos--scripts,gtank/scripts,vmware/coreos-scripts,sigma/coreos-scripts,nicescale/scripts,mischief/scripts,andrejro/coreos--scripts,mjg59/scripts,marineam/coreos-scripts,nicescale/scripts,mischief/scripts,sigma/coreos-scripts,gtank/scripts,mischief/scripts,BugRoger/scripts,crawford/scripts,endocode/scripts,crawford/scripts,zhang0137/scripts,bcwaldon/coreos-scripts,mjg59/scripts,coreos/scripts,vmware/coreos-scripts,trnubo/scripts,sigma/coreos-scripts,bcwaldon/coreos-scripts,marineam/coreos-scripts,mjg59/scripts,glevand/coreos--scripts,marineam/coreos-scripts,BugRoger/scripts,endocode/scripts,zhang0137/scripts,nicescale/scripts,crawford/scripts