[important] Change license of Emperor to BSD

All files were changed to a BSD license and some functions were changed
as a consequence of this.

Can the following authors respond whether or not they agree with the change of
licensing for this software.

Code related with QIIME/EMPeror

- [x] @meganap
- [x] @antgonza
- [x] @jacksonchen
- [x] @eldeveloper

Code related with QIIME/PyCogent:

- [x] @gregcaporaso
- [x] @justin212k
- [x] @jrrideout
- [x] @danknights
- [x] @clozupone
- [x] @rob-knight
- [x] @RNAer

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I'll check the boxes as people respond to this message.