Js docs

[FreeMasen]

This addresses two of the 3 remaining items in #57, all user exported functions will now be annotated with the JSDoc @param and @returns statements.

Upon further investigation into applying the @constructor statement I discovered that we are still using the class keyword when using no-modules, meaning that this would not be required.

This should effectively close #57 unless we are looking to provide an output that uses the function constructor + prototype syntax.

[FreeMasen]

Looks like this is currently breaking the JS formatting due to the JSDoc convention of including type information inside of {}. Since these new lines end with a } they are being incorrectly formatted.

#427 is pending and re-writes the formatting code entirely so I am going to hold out on a fix until that gets merged.

[alexcrichton]

Looks great, thanks!