Collapsible Accordion implementation for network module's connection_show.html file

Created by: nikhilrayaprolu

worked on the issue https://github.com/freedombox/Plinth/issues/322 where I have added the bootstrap's collapsible accordion property here. # #322 (closed)

I have tested it on my pc on both not activated and an activated network and has worked fine. here I am pasting a preview image of the output collapsible http://imgur.com/LHaOq4j