restore and improve index page

remove the proposal display from index page
fix index button to send user to proposal listing
add horiz rule to every page before footer

this way it separates content from footer, now it's normalized by
base.html template
include another sorting criteria (Recent)

"Recent" uses sorts by timestamp, which was the default sorting order,
now it has its own tab. Clarify semantics of the other criterion.
refactor code and normalize website design

Content is centered (span 10 offset1); Score is display is more compact;
Titles are H1 and are followed by a break like; Navbar changes according
with current page; Add link to "Make a proposal"