Allow to specify a whitelist and a blacklist of net access. See #217.

This is my last pull request as an intern on the Mozilla Security
Assurance team.

What hasn't been implemented is the abililty to resolve the target
to the IP addres within the scan.

This is due to time constraint; I need more time
to develop a test case (maybe I overthink, maybe just localhost
is a fine test case, maybe). It is relatively very easy to add that
check anyway. I already have the resolver function implemented
in utils.py

The changes are to allow a "scna.json". We will extend the network
access before saving the target url to database in the future
commits.

The test includes two sample JSON. One with both blacklist and whitelist
empted and one with a blacklist. We are using ipaddress to determine
whether or not an ip is part of a whitelist (remind: anything
not in blacklist is automatically consider whitelisted).

I also want to be able to specify ports in the future (whitelist
a particular port on 192.168.1.1)).

We can do this once this implemented is accepted.

Anyway. I have had a great time at Mozilla. See you on #websectools.

*rawr*
Fixes #228 Unit tests should stop calling sudo kill

I have removed this code completely. If it turns out to be a problem
then we can investigate a solution that does not require executing shell
commands as root.
Fixed #227. There was a raw_input debug code left inside the test.
Fixes #229 Skip hsps_no_hsps_header_over_https if stunnel4 is not installed

Also simplifies stunnel process management. Properly terminate stunnel.
Fixes #230 Fix spelling mistakes in test_hsts
Fixes #227 Tests are hanging
Merge pull request #231 from yeukhon/issue##227

Fixed #227. There was a raw_input debug code left inside the test.
Fixes #233 Test failures in functional/views/test_groups.py
Fixes #225 Scan remains in STARTED state if plugin execution fails
Merge branch 'issue#217' of https://github.com/yeukhon/minion-backend into yeukhon-issue#217

Conflicts:
	minion/backend/tasks.py
Fixes #239 Blacklist should have default list of standard non-routable networks
Fixes #241 Blacklist should have better unit tests
Multiple Blacklist fixes

* Fixes #236 Blacklist fails when interpreting hostname as an ip address
* Fixes #237 Blacklist should use standard network/prefix notation
Removed test_utils because the blacklist tests are now in test_blacklist
Fixes #242 Aborted scan still has plugin sessions in CREATED state
Cleanup up the imports of tasks.py
Fixes #244 Remove old Twisted code to execute plugin-runner from tasks.py
Fixes #243 Cancelled plugin sessions show a duration of 16 days
Fixes #223 Remove demo sites from minion-db-init
Fixes #246 Blacklist check fails on targets that have their port specified