readme: add temp handling of nokogiri and mini_magick
browser.rb: add $using_webdriver global set by querying actual instantiated browser/driver.
rename awtestlib_helpers check_script_type to parse_script_type to remove confusion with method in runner.rb.   Add 'AwetestDSL', 'Awetestlib', 'Awetest' script type synonyms for 'Regression'