created basic help functions
small performance fix
Admin: added external networks and instances
started moving common admin web functionality into one file
added big connect icon
removed erroneous import
removed django cache commands from host/site list
merged from dswd
Merge branch 'master' into working_admin
integrated help into tutorial; created a first help page
wrote first tutorial (without trigger checks)
topology list: moved new/import buttons under the list, so that they are not visible from the editor anymore.
prepared topology import: file upload
small cleanup
completed implementation of external networks admin
implemented external network interfaces: web admin
cleanup: dropdown lists now created in __init__
continued work on help; small cleanup in topology.py
Merge remote-tracking branch 'dswd/master'
Merge branch 'working_editor'