Support >2 and JSON-formatted options in parser tests.

The parserTests options handling had a regex capture bug which caused
it to discard all but the first and last option values.  Fix this (by
separating value splitting from key/value capture).

Add support for JSON-valued options, which parsoid would like to begin
using.  Add support for backslash escapes in quoted strings.

Change-Id: I69323bb44b7a481bad6f490d0773a984239c0b9c
Merge "Support >2 and JSON-formatted options in parser tests."