Added the MIT license

LICENSE.md

@@ -0,0 +1,22 @@
+Optim.jl is licensed under the MIT License:
+
+> Copyright (c) 2012: John Myles White and other contributors.
+> 
+> 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.