Added MIT license to gemspec

Fixes issue #226 reported by @bf4.

LICENSE

@@ -1,4 +1,4 @@
-Copyright (c) 2012 Jamon Holmgren
+Copyright (c) 2013 Jamon Holmgren
 
 MIT License
 
@@ -19,4 +19,4 @@ 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.
+WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

ProMotion.gemspec

@@ -12,6 +12,7 @@ Gem::Specification.new do |gem|
                         utilities to make iOS development more like Ruby and less like Objective-C.
                       "
   gem.homepage      = "https://github.com/clearsightstudio/ProMotion"
+  gem.license       = 'MIT'
 
   gem.files         = `git ls-files`.split($\)
   gem.executables   = gem.files.grep(%r{^bin/}).map{ |f| File.basename(f) }