Move to grunt for building all distribution files.

* canonical version number of jasmine-core is now is package.json
* `grunt buildDistribution` builds jasmine.js, jasmine-html.js, jasmine.css and outputs them to the dist dir
* `grunt buildStandaloneDist` builds the example spec runner files and compresses them to dist/jasmine-VERSION.zip
* `grunt compass` compiles jasmine.css
* jasmine.Env handling of version is backwards compatible, but uses the version string directly (and nicely deprecated)
* Ruby/thor tasks that did the above deleted

tasks/jasmine_dev/execute_specs.rb

@@ -5,7 +5,7 @@ class JasmineDev < Thor
   def execute_specs_in_node
     return unless node_installed?
 
-    invoke :build_distribution
+    `grunt buildDistribution`
     invoke :count_specs
 
     say JasmineDev.spacer
@@ -20,7 +20,9 @@ class JasmineDev < Thor
   desc "execute_specs_in_browser", "Run all relevent specs in your default browser"
 
   def execute_specs_in_browser
-    invoke :build_distribution
+    return unless node_installed?
+
+    `grunt buildDistribution`
     invoke :count_specs
 
     say JasmineDev.spacer