Make npm dependency usable by Browserify through npm

typo

Added support for standard transforms

-webkit- stuff only works on webkit browsers.  I'm pretty sure that using the standard `transform:` here works in most modern browsers.

update marked to 0.3.3

Compressed with `uglifyjs lib/marked.js --comments="/Copyright/" --mangle --compress`

Used Marked v0.3.3 as of chjj/marked@2b5802f258c5e23e48366f2377fbb4c807f47658

see https://github.com/hakimel/reveal.js/issues/929#issuecomment-80738837

Right now the package is not recognized as usable library by Browserify.
Adding the main attribute in the package.json solves that, and now gives
others the possibility to use reveal as a library in more complex
systems.