Add LICENSE.md

[EntityPlantt]

Should add LICENSE.md, for GitHub to recognize that this project is licensed.

^^^ Should appear that is has a license, but it doesn't.

For PR

./LICENSE.md:

+ This software is licensed under the MIT License.
+ 
+ Copyright Fedor Indutny, 2012.
+ 
+ Permission is hereby granted, free of charge, to any person obtaining
+ a copy of this software and associated documentation files (the "Software"),
+ to deal in the Software without restriction, including without limitation the
+ rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ sell copies of the Software, and to permit persons to whom the Software is
+ furnished to do so, subject to the following conditions:
+ 
+ The above copyright notice and this permission notice shall be included
+ in all copies or substantial portions of the Software.
+ 
+ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE
+ OR OTHER DEALINGS IN THE SOFTWARE.