Uses uni-form to style forms and add a macro to ease this.
Of course, the overall thing has to be reworked, but having this in place will
help us to have something easier to change when we will really care about design.
All the form templates can now be defined in templates/forms.html and be called
thansk to {{ forms.name_of_the_form(form) }}.
I've done some styling, but that's really not my thing, feel free to modify it.
