Add a scripts block to layout

The scripts block is for different .js that would be loaded in
different pages.

new file:   public/javascripts/tags.js
  This file is for the tellusadmin/tags page. It will construct the
  backbone structure for the needed contents
Use the backbone-way to rebuild the code and API
Add the different ordering and the edit event

modified:   views/admin/tags.jade
With the <th> field in the TagList, use html5 data-* to discover the
comparator, remove the _id in table, add lastModified and lastModifier
field to the TagList.

modified:   public/javascripts/tags.js
Modified the order function in the tagView, let this function to handle
different comparator. Add a event for editting tag.
Modified the .gitignore for example config file
Typo correction
Add the buttons for edit and delete
Merge pull request #2 from shingo0620/master

update