Update the sample web.config

Initial user will most likely copy this sample web.config the first
time. This commit fix the "DefaultConnection" connection string name and
added captcha  settings.
Fix the hardcoded captcha public key

Use web.config settings instead
Fix more hardcoded captach
Change 'DefaultConnection' to 'whoaverseUsers'
Revert "Change 'DefaultConnection' to 'whoaverseUsers'"

This reverts commit 71c68dc42e2aa6bbd6aba184830c459959714c5c.
Replace 'DefaultConnection' with 'whoaverseUsers'
Merge pull request #190 from dodyg/master

Update the sample web.config and readme. Fix further hardcoded captchas.