Remove tools/glance-jeos-add-from-github.sh

glance-jeos-add-from-github.sh has not been edited since 2012-08-20, and
its image links have been broken (according to Google cache) for a
minimum of 9 months.

The functionality of the script seems to be superceded by the
handy-dandy diskimage-builder tool.

See http://docs.openstack.org/developer/heat/getting_started/jeos_building.html
for more info about diskimage-builder workflow.

Change-Id: I99880f1cca4af84fa7193d749a7c8f6957bb0b78
Partial-Bug: 1338066
Move network constraint to neutron plugin

This allows exception imports to be encapsulated inside the neutron
plugin, and plugins are likely the most appropriate place for
custom constraints to live.

Change-Id: I5766edb305b7cfffdcd8943fb6edce7f3e9ff26d
Merge "Move network constraint to neutron plugin"
Merge "Remove tools/glance-jeos-add-from-github.sh"