Added the new `Includes OpenSSL Cryptography Software' button as

doc/openssl_button.{gif,html} which is similar in style to the old SSLeay
button and can be used by applications based on OpenSSL to show the
relationship to the OpenSSL project.

PS: This beast caused me three hours to create, because
    of the size I had to hand-paint the 7pt fonts in Photoshop.