Adding CURLOPT_TIMEOUT with the same timout as CURLOPT_CONNECTTIMEOUT.

This change adds the CURLOPT_TIMEOUT option, so that a hanging
connection won't hang indefinately.

It adds test for this option, and also fixes the test for
CURLOPT_CONNECTTIMEOUT (that was typoed into CURLOPT_RETURNTRANSFER
and missed because of assertEquals instead of assertSame).