Move zk.wcs to static assets folder (i.e. get rid of ".css.dsp")

User Story

As a user, I want Http server to serve all static assets, such as Image, JS, and CSS, so that it's better to get rid of zk.wcs for CSS files by using pure CSS file instead.

All less files are also to convert to pure CSS files instead of DSP files.

Acceptance Criteria

All assets can be put outside Application server (i.e. Tomcat or Jetty), the user can specify it into a Nginx or Apache server to serve, if not specified, the assets can also be served by ZK server inside a jar or similar mechanism.