Update gradle build files to 0.7.3 android plugin, add Gradle 1.9 wrapper, add information about build to readme

libraries/ActionBarSherlock/build.gradle

@@ -15,4 +15,9 @@ android {
       res.srcDirs = ['res']
     }
   }
+  
+  // Do not abort build if lint finds errors
+  lintOptions {
+      abortOnError false
+  }
 }