Updated tested-with in cabal file.
Merge branch 'master' of github.com:jgm/pandoc
Merge branch 'master' of github.com:jgm/pandoc
Fixed regressions in fenced code blocks.

*   Tilde code fences can again take bare language.

    So

        ~~~ haskell

    is okay, not just

        ~~~ {.haskell}

*   Backtick code blocks can take the bracketed attributes.
*   Backtick code blocks don't require a language.
*   Consolidated code for the two kinds of fenced code blocks.

Closes #722.