Remove MIT license header from source files

[dvdsgl]

We can license this app with a single license file at the root of the repo. I just watched a recorded demo and the big MIT comment block at the beginning of each file was a distraction, and also made Xamarin look 'open sourcey'.

[jsauvexamarin]

I was instructed by motz to do this. I can remove if necessary. Either that or you can set your IDE to collapse those comment blocks for demos.

[dvdsgl]

I spoke with Miguel about it and he agrees we should remove it for cleaner samples.