Responsive-ish Kawaii-CSS

The focus of this minor release was to convert all px to em so that the framework is responsive-ish.

- You can now control the size of the Kawaii character by changing the font size. The default is 10px.
- Twitter Bootstrap has been used in the example page for responsive layout, but it is not required when using Kawaii framework.
- In the example, you can compare the new responsive Kawaii versus v0.0.1. 
- Corrected a behaviour where Box-sizing is applied differently and not consistent on all elements. Previously it was preventing users from using Kawaii-CSS together with normalised CSS or frameworks such as Twitter Bootstrap.