Fix cut tooltips when inside elements with overflow:hidden

Tooltips are now appended to the <body> that, so doesn't matter how the tooltip's
parent css is defined, it should always work.
Also tooltips don't need a min-width anymore.
Add css mixin to deal with broken images, complements 9f932629790

Almost the same that was done before, but now everything is done by a mixin.
It was also improved a bit.
Improvements in LogoImagesHelper

Was including the url attribute in <img>, but shouldn't.
Nothing else changed in the functioning, only refactored a bit and added pending
tests.
A lot of improvements in events, specially for views, refs #383

Made the views we use look better, and at the same time refactored and removed
*a lot* of things related to them. Few changes in controllers/models, most
where in the views and related assets.
There's still a lot to be improved, specially in the controller.
Cleanup and improvements in events, mostly for the controller, refs #383

Cleaned up the controller a lot and added tests (most pending).
Includes some changes in the views too, complements 18091c76cdb.