add MIT license and update gemspec

LICENSE

@@ -0,0 +1,22 @@
+The MIT License (MIT)
+
+Copyright (c) 2008-2013 TJ Holowaychuk <tj@vision-media.ca>
+
+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.

commander.gemspec

@@ -7,6 +7,7 @@ Gem::Specification.new do |s|
   s.version     = Commander::VERSION
   s.authors     = ["TJ Holowaychuk", "Gabriel Gilder"]
   s.email       = ["ggilder@tractionco.com"]
+  s.license     = "MIT"
   s.homepage    = "http://visionmedia.github.com/commander"
   s.summary     = "The complete solution for Ruby command-line executables"
   s.description = "The complete solution for Ruby command-line executables. Commander bridges the gap between other terminal related libraries you know and love (OptionParser, HighLine), while providing many new features, and an elegant API."
@@ -23,4 +24,4 @@ Gem::Specification.new do |s|
   s.add_development_dependency("rspec", "~> 2")
   s.add_development_dependency("rake")
   s.add_development_dependency("simplecov")
-end
+end