Update cabal file and add license

LICENSE

@@ -0,0 +1,3 @@
+Dual licensed under the MIT and GPL licenses:
+http://www.opensource.org/licenses/mit-license.php
+http://www.gnu.org/licenses/gpl.html

shortener.cabal

@@ -1,18 +1,29 @@
 name:                shortener
 version:             0.0.1.0
+synopsis:            a url shortener
+description:
+  
+  A web application that provides a simple interface to shortening
+  long urls creating smaller and easy to remember links.
+
+homepage:            https://github.com/rnhmjoj/shortener
+license:             MIT
+license-file:        LICENSE
 author:              Rnhmjoj
 maintainer:          micheleguerinirocco@me.com
+copyright:           (C) Michele Guerini Rocco 2015
 category:            Web
 build-type:          Simple
-cabal-version:       >=1.8
+extra-source-files:  README.md, LICENSE
+cabal-version:       >=1.10
 
 executable shortener
   main-is:           Main.hs
-  ghc-options:       -threaded -O2
+  default-language:  Haskell2010
   build-depends:     base, simple >= 0.8.0, 
-                     wai, wai-extra,
-                     warp, aeson,
-                     transformers, mtl,
-                     hashtables, cryptohash,
-                     bytestring, binary, random, 
-
+                     wai ==2.*, wai-extra ==2.*, warp ==2.1.*,
+                     aeson ==0.8.*, bytestring ==0.10.*,
+                     transformers ==0.3.*, mtl ==2.1.*,
+                     hashtables ==1.2.*, cryptohash ==0.11.*,
+                     binary ==0.7.*, random ==1.1.*
+  ghc-options:       -threaded -O2