Re-implemented all development Rake tasks in Thor. Now actually tested.

Fixes:
* https://www.pivotaltracker.com/story/show/25484287 & https://github.com/pivotal/jasmine/issues/183
* https://www.pivotaltracker.com/story/show/25485401 & https://github.com/pivotal/jasmine/issues/189
* https://www.pivotaltracker.com/story/show/25485953 & https://github.com/pivotal/jasmine/issues/159

tasks/jasmine_dev/base.rb

@@ -0,0 +1,56 @@
+class JasmineDev < Thor
+  include Thor::Actions
+
+  def self.source_root
+    File.dirname(__FILE__)
+  end
+
+  def self.source_paths
+    [
+      File.join(JasmineDev.project_root, 'lib', 'jasmine-core'),
+      JasmineDev.project_root
+    ]
+  end
+
+  def self.project_root
+    File.join(JasmineDev.source_root, '..', '..')
+  end
+
+  def self.spacer
+    "\n--------------------"
+  end
+
+  no_tasks do
+    # allows merged stdout in test with low-harassment
+    def run_with_output(*run_args)
+      say run *run_args
+    end
+
+    def node_installed?
+      return true if has_node?
+
+      say "Node.js is required to develop Jasmine. Please visit http://nodejs.org to install. ",
+          :red
+      false
+    end
+
+    def has_node?
+      run "which node", :verbose => false, :capture => true
+      last_exit_code = $?.to_s[-1]
+
+      last_exit_code == '0'
+    end
+
+    def pages_submodule_installed?
+      return true if has_pages_submodule?
+
+      say "Submodule for Github Pages isn't present. Run git submodule update --init",
+          :red
+      false
+    end
+
+    def has_pages_submodule?
+      File.exist?(File.join(JasmineDev.project_root, 'pages', 'download.html'))
+    end
+  end
+end