GROOVY-6625: Sql failed to process query unterminated ' character

ExtractIndexAndSql was not properly handling parsing of quoted strings when there were multiple consectutive quotes at the beginning of the string (e.g. select '''s for plural' from dual).
Merge pull request #360 from jwagenleitner/GROOVY-6625

GROOVY-6625: Sql failed to process query unterminated ' character, thanks!