Reverted cache.js. Cannot fully generate from source

Cache.js interacts with the file system by loading JSON. Its behavior for jS is
not the same as the behavior when run under Ruby, and as of now the JS version
cannot be generated verbatim. This can be fixed eventually.
Moved Piping from ../demos to /demo

RequireJS does not parse paths with ".." properly, so files that are translated
to Javascript should not appear outside of /src. Long-term goal is to move
everything else to avoid dealing with files outside /src
Reshuffled various documentation
Moved ../demos to demo

Javascript is unable to correctly process Ruby files outside of src/. This is
because the translator will produce a Javascript path that is outside of js/
and requires.js cannot handle relative paths (it's an open bug).
Merge branch 'master' of https://github.com/enso-lang/enso

Conflicts:
	src/js/core/system/load/cache.js