Unexpected result on Submitting form without verifying captcha.

When submitting the form without verifying captcha. One shouldn't be able to submit the form.
But this doesn't happen, instead we get redirected to
`https://cbemail.herokuapp.com/?error=1#form`
and response is
`{"message":"There is no God"}`

**Expected Behaviour:**
One shouldn't be able to submit the form until the captcha is verified.

**Current Behaviour:**
Form getting submitted,
Getting redirected to `https://cbemail.herokuapp.com/?error=1#form`
with response `{"message":"There is no God"}`

首先，在不验证 captcha 的情况下复现 issue 中描述的表单提交，然后跟踪表单和 captcha 的验证流程。当未验证的 captcha 阻止提交，且报告的重定向和错误响应不再发生时，即表示完成。

由索引模型根据 Issue 内容生成。