Update grunt-contrib-compress dependency and swich to release tarballs

To resolve file mode issues with the .zip release files, this switches
to using tarballs instead.

Author: ericf

Gruntfile.js

@@ -130,7 +130,7 @@ grunt.initConfig({
     compress: {
         release: {
             options: {
-                archive: 'release/<%= pkg.version %>/<%= pkg.name %>-<%= pkg.version %>.zip'
+                archive: 'release/<%= pkg.version %>/<%= pkg.name %>-<%= pkg.version %>.tar.gz'
             },
 
             expand : true,

package.json

@@ -14,7 +14,7 @@
     "grunt-contrib-clean": "~0.5.0",
     "grunt-contrib-copy": "~0.5.0",
     "grunt-contrib-concat": "~0.3.0",
-    "grunt-contrib-compress": "~0.5.0",
+    "grunt-contrib-compress": "~0.6.0",
     "grunt-contrib-csslint": "~0.2.0",
     "grunt-contrib-watch": "~0.5.3",
     "grunt-css-selectors": "~1.0.0",