Dev

I've done large refactoring, the code is well organized now, Here is short summary:
— created file-upload directive with all needed staff
— removed content (html. etc) from controllers
— configuring of nextSteps was moved to config/join.js
— ModalControllers were simplified
— added factory to signup object
— simplified controllers
— fixed crazy validation of start form
— used nested views for confirm and done steps to avoid duplicity of content

I found 2 drawbacks:
1) "confirmation" and "done" steps are implemented with additional nested ui.view. It leads to animation only on "footer" and "header" section (content section is not changeable). To avoid the animation, I blocked it by adding class="without-animation" and changing app/styles/app.scss. It can be fixed by using ng-include. 
2) signup data will be appear again if you restart signup process by changing url or some other way. It can be easily fixed by adding a method to signup class.

As I see join block is not completely ready so it can be fixed in the future when other join functionality will be implemented.