Conflicts:
	flowspy/settings.py.dist

By mistake, regular expression for portranges did not accept port 0.
Fixed.

Unfinished tasks caused problem with repeating snmp polling

fod currently uses local copy of chartjs instead of remote file from cdn

It is performed as a celery task every 5 minutes according to
settings.py.
The views.py doesn't contain direct call of snmp_get_data() anymore, it
just looks up data stored in SNMP_TEMP_FILE.

It is now possible to specify the port number of the community string
for each IP separately.

The example is shown in settings.py.dist.

It is polled using SNMP from the list of SNMP devices.
New variables in settings.py are expected.

The retrieved statistics are shown in a simple graph.