Improve the help text for the linuxnet options (1)
Improve the help text for the linuxnet options (1)

The previous commit moved all the options from network/linuxnet.py to a
central location in nova/conf/network.py. This commit adds additional
help text to those options.  Because of the large number of options, the
improved help text will be split into several patches; this is patch 1
of 4.

Blueprint centralize-config-options-newton

Change-Id: I79b587aa6bba902f53c786646f47f610ca9bc2fd

openstack/nova,sebrandon1/nova,cloudbase/nova,mahak/nova,openstack/nova,klmitch/nova,rahulunair/nova,vmturbo/nova,gooddata/openstack-nova,mahak/nova,vmturbo/nova,cloudbase/nova,phenoxim/nova,klmitch/nova,mikalstill/nova,alaski/nova,rahulunair/nova,cloudbase/nova,rahulunair/nova,rajalokan/nova,gooddata/openstack-nova,jianghuaw/nova,openstack/nova,mahak/nova,vmturbo/nova,rajalokan/nova,Juniper/nova,klmitch/nova,Juniper/nova,klmitch/nova,rajalokan/nova,sebrandon1/nova,sebrandon1/nova,zhimin711/nova,hanlind/nova,mikalstill/nova,gooddata/openstack-nova,Juniper/nova,vmturbo/nova,hanlind/nova,rajalokan/nova,Juniper/nova,zhimin711/nova,gooddata/openstack-nova,hanlind/nova,bigswitch/nova,jianghuaw/nova,alaski/nova,jianghuaw/nova,bigswitch/nova,jianghuaw/nova,phenoxim/nova,mikalstill/nova