fix the json example to use alt/seq correctly
breaking: deprecated chaining use of .then()
breaking: no longer throw parse errors

instead, return objects with status tags.

Use

    Parsimmon.formatError(source, error)

to get a string similar to what was thrown in previous versions.
update the README to reflect new api changes
Merge branch 'refactor.no-errors-and-also-chain'

Conflicts:
	src/parsimmon.js