Work In Progress - New Documentation

In this WIP branch, we are creating extensive documentation for the complete ValidForm Builder API.
This documentation will be written inline with each class and public method and auto-generated with PHPDoc.
The documentation should eventually be published as GitHub Wiki pages.

# Update
Boom! All done! A two week marathon session did the job; all classes are fully documented with examples.
All that's left is to double check the code, the [generated docs](http://validformbuilder.org/docs) and this branch to merge it with master.

## Todo
- [ ] ~~Update Travis CI's Composer GitHub API requests limit:~~
This is not really a required to-do but more a 'nice to have' in the upcoming releases. Won't make it to the `3.2` release.
http://blog.simplytestable.com/creating-and-using-a-github-oauth-token-with-travis-and-composer/

- [x] Setup and configure Travis CI
- [x] Write Area documentation
- [x] Write Button documentation
- [x] Write Base documentation
- [x] Write ClassDynamic documentation
- [x] ~~Write Captcha documentation~~
- [x] Write Checkbox documentation
- [x] Write Collection documentation
- [x] Write Comparison documentation
- [x] Write Condition documentation
- [x] Write Fieldset documentation
- [x] Write File documentation
- [x] Write Group documentation
- [x] Write GroupField documentation
- [x] Write Hidden documentation
- [x] Write MultiField documentation
- [x] Write Navigation documentation
- [x] Write Note documentation
- [x] Write Page documentation
- [x] Write Paragraph documentation
- [x] Write Password documentation
- [x] Write Select documentation
- [x] Write SelectOption documentation
- [x] Write SelectGroup documentation
- [x] Write String documentation
- [x] Write Text documentation
- [x] Write TextArea documentation
- [x] Write ValidForm documentation
- [x] Write ValidWizard documentation