Disable W3TC object caching when captcha is used (until a cache friendly captcha solution is added)

Signed-off-by: Nick Ciske <nick@thoughtrefinery.com>
Add Content-Type header to form POST

Signed-off-by: Nick Ciske <nick@thoughtrefinery.com>
Version bump

Signed-off-by: Nick Ciske <nick@thoughtrefinery.com>