Remove extra instance of 'network' in modules.list

The modules.list file currently contains two occurances of the
'network' module.  This is harmless as apt-get just figures out
that you've asked for the same module twice, but should be tidied
up anyway.  This commit removes one of the redundany occurances.

Closes-Bug: #1227124
Merge pull request #177 from CiscoSystems/bugs/1227124

Remove extra instance of 'network' in modules.list