Make piler compatible with Express 3.x

Fixed the compatibility issues for Express3 basically i included the fix from PR https://github.com/epeli/piler/pull/29 which fixes https://github.com/epeli/piler/pull/26

  * Extended the documentation to use the bundle with ExpressJS 3. 
  * Fixed a problem with live updated CSS which is not triggered in development mode (express3)
  * Fixed a problem with asset update URL calculation when a live update is triggered in development mode. (express3)

Any chance of getting a updated piler NPM package with this fixes?