allow to specify multiple target accesspoints (by bssid or essid)

[tintinweb]

• added handling for multiple --accesspoint filters --accesspoint now takes essid or bssid tracks bssid's for essid's essid is case sensitive bssid is not case sensitive
• added utf8 coding hint
• fixed wrong indentation (sniff())

Allows to specify multiple targets by either bssid or essid. Selection by essid is way more handy than bssid. Here's an example to jam FreeWifi, UnitedCoffee and others:

tin@debian8:~/wifijammer$ sudo python wifijammer.py --accesspoint "FreeWifi" ff:53:cc:f2:8A:E3 ba:df:00:00:00:0d "UnitedCoffee" Starbucks

[DanMcInerney]

merged the other one.

[tintinweb]

@DanMcInerney this one is actually different from #61 as it allows to specify multiple target bssids or essids whereas #61 allows to specify bssids to skip. Plus it fixes an indentation. Would appreciate a merge. Thanks.

[DanMcInerney]

Can you fix the minor conflicts and I'll merge?

[tintinweb]

done 👍