Added houston_ruleset_parser.js.  It is a lexer and parser for the Houston Ruleset (HRS) domain-specific language (DSL). HRS is a convenient web-developer-friendly representation of Houston's ruleset dictionary inspired by Cascading Stylesheets (CSS). Houston's ruleset dictionary is optimized for performance, not human readability. Although it can be easily represented in JSON format, it can often become confusingly recursive and overly verbose. HRS is a higher-level language which sits on top of the lower-level ruleset dictionary.