Add license text to repository

[Simon Fondrie-Teitler]

The README currently says "Hallo is free software available under the MIT license." However, this can mean many things. The wikipedia article states:

Because MIT has used many licenses for software, "MIT License" is considered ambiguous by the Free Software Foundation. "MIT License" may refer to the "Expat License" (used for Expat) or to the "X11 License" (also called "MIT/X Consortium License"; used for the X Window System by the MIT X Consortium).

You may mean the expat license, shown here:
http://www.debian.org/legal/licenses/mit

It would be great if you could add a LICENSE.txt file to the repo witha copy of the license to clarify this. This will help with other projects wanting to use the code.

Thanks a lot,
Simon Fondire-Teitler