Fixed literals syntax for iOS 5

I'm using Analytics in a iOS5+ project and when running the app on iOS5 it crashes with 
```
[__NSCFDictionary setObject:forKeyedSubscript:]: unrecognized selector sent to instance 0x8a7f910
```
To replicate just run the test on the Analytics project on iOS5 simulator.
This PR uses code from https://gist.github.com/jaydee3/3314686