Support for Zero args and CocoaPods

[staxmanade]

Hello,

Found your project and loved it's elegance!

This pull requests has the following updates:

• Updated to support zero argument version of PubSub0(subName).
• Added an explicit MIT license file
• Created a podspec file
• Changed the parameter to not automatically add a * to the arg. So PubSub(name, NSString) becomes PubSub(name, NSString*)
• Replaced the generic PubSub(...) macro with argument specific ones PubSub0(name), PubSub1(name, type, argName)`...
• Support argument names within the PubSub(name, NSString* argNameHere)
• Supports 0..3 arguments at the moment.

If you like any of these changes and consider merging them in, you'll want to update the PubSub.podspec to point to your name/project.

Potential issue???

• I'm currently ripping use of this project out as I keep seeing random crashes

Future desire:

• This does not handle 'value' types well so int/BOOL etc. Not sure if there is a way around this, but would like to figure that out as well.

Thoughts?