Handle twitter URLs being pasted

People often paste full twitter URLs into their "twitter" field. This will display those properly.
redirect npmjs.org/?searchTerm -> npmjs.org/search?searchTerm

Per https://twitter.com/_jden/status/329027361716723712, redirect empty path with qs
to search route, especially for use when manually typing urls with npm.im.
Support npm.im?search-terms also