Change license to MIT

[dola]

After a decision by all contributors, the license will be changed to MIT.

Todo:

• change license file
• update license in package.json

Maybe:

• add header to all files with license (would not recommend)

[dola]

PR #54 contains the necessary changes:

• new LICENSE file with MIT license (rename from LICENSE.txt)
• remove license from source code file headers (was in index.js)
• add to changelog for version 3.0.2
• reference LICENSE file in README.md
• build entire project

[bruderol]

@adiherzog and @dola i close this