Migration for ionic@beta.22

[mavogel]

The ionic2 framework made in version beta@22 a couple of changes so that the clicker app did not run properly any more. For example:

• The 'app.bundle.js' was not found any more from the browser because of a big refactoring of the 'gulpfile.js'.
• The 'ionic.config.js' was also replaced by a 'json'-file.
• The content of the 'www/index.html' file changed.

I used the ionic2-starter-tutorial as reference and adapted the config files. So all the users who install ionic without a specific version

$ npm i -g ionic@beta

can now use your great project as a base again.

[lathonez]

@mavogel very much appreciated, thank you.