Use system proxy & update read me

@homebysix let's include this in the 1.1.1 release too.
There is a new pod http://cocoadocs.org/docsets/AHProxySettings/0.1/ so you'll need to do `pod update` and will most likely need to clean your build folder.

It really seemed to work where the other methods weren't in #187
It also added the ability to manually set NO_PROXY so that's an improvement too.

Let me know if you have any questions.