Fix when Quality = ''

[darryllee]

Some APs are returning Quality values of single integers instead of x/100. I'm not sure why, but getCellQuality doesn't seem to recognize a single integer, and so Quality ends up being set to '', per the default value set in line 157.

Unfortunately, when sortNetworks then tries to figure out a sorting factor, it assumes there will be a slash, and we get the error: Unhandled exception 'need more than 1 value to unpack' at /usr/lib/python2.7/dist-packages/kano/network.py line 225

I couldn't figure out why getCellQuality isn't able to deal with a single integer Quality, but I was able to workaround these weird APs (luckily neither of them is mine) by setting factor to 0 if Quality = ''.