Add fragment caching to responsive layouts.

Cache key is built in 3 variants:
1) [__FILE__] - when there is no dynamic content at all
2) [__FILE__, local_assigns.map(&:to_s)] - when we pass some control variables
3) same as 2 + Rizzo::COMMIT - it depends on data provided by helpers,
therefore it can't be invalidated by calculating view digest. It will be
invalidated on each commit.

I've added cache only to responsive layout, other left untouched.