Emmanuel.Cryptography.GnuPG.GnuPG.CryptAndSignButton_Click Function
Callback function when a user clicks on CryptAndSignButton. Processes the input
text from MessageTextBox control via GnuPG and displays the output into
OutputTextBox control.
Please note that this function reads the following keys from Web.Config and
passes them to the GnuPGWrapper class: "homedirectory" and "passphrase".