Various tweaks:

* use grunt 0.4.2
* always use latest mocha for dev
* update boilerplate devDeps
Fix js assets
Fix depcreated assert when update yeoman generator 0.16.0
Update template README info

* add appName to header
* link to Assemble docs, plugins and helpers
* generate history change for 0.1.0
Prompt for project description
Option to force question and re-generating .yo-rc.json

Command:
    yo assemble --init

Alias:
    yo assemble -i

Enable user to rewrite/replace boilerplate for existing project. File conflict manage by Yeoman.
v0.4.6
Merge pull request #33 from assemble/develop

v0.4.6