Allow parsing empty values for options in CLI arguments

If an option is passed via CLI, it cannot be passed with an
empty value because the Regex makes it to match 1 or more
characters.

For example, arguments `--mock_prefix=""` and `--mock_prefix=`
are invalid, because they don't match the regex and are not
recognized as options, so they're treated as files to mock.

Changing the regex to match 0 or more characters for the option
value, instead of 1 or more, solves the problem.

lib/cmock.rb

@@ -89,7 +89,7 @@ if $0 == __FILE__
       options.merge! CMockConfig.load_config_file_from_yaml(arg.gsub(/^-o/, ''))
     elsif arg == '--skeleton'
       options[:skeleton] = true
-    elsif arg =~ /^--([a-zA-Z0-9._\\\/:\s]+)=\"?([a-zA-Z0-9._\-\\\/:\s\;]+)\"?/
+    elsif arg =~ /^--([a-zA-Z0-9._\\\/:\s]+)=\"?([a-zA-Z0-9._\-\\\/:\s\;]*)\"?/
       options = option_maker(options, Regexp.last_match(1), Regexp.last_match(2))
     else
       filelist << arg