Add failing tests for single quotes inside string.

Per [1], [2] and [3], a single quotation mark `'` has to be replaced by
`''` in a string literal.

- [1]:http://pic.dhe.ibm.com/infocenter/idshelp/v117/index.jsp?topic=%2Fcom.ibm.gen_busug.doc%2Fc_fgl_sql_programming_080.htm
- [2]:http://www.postgresql.org/docs/9.3/static/sql-syntax-lexical.html#SQL-SYNTAX-STRINGS
- [3]:http://dev.mysql.com/doc/refman/5.0/en/string-literals.html
Fix failing tests for single quotes in strings.

Make everything use the same method for escaping. It was couple of
inline `.replace` calls before (in base and mysql drivers).