Revert "remove .php from links in navbar"

This reverts commit d0c2047e4331fadf7c4e6e00e82a5fa8b1c07562.
Revert "Added ajax to send the email from the contact page as well the PHP code to actually send it."

This reverts commit 44492b3203f3cba72ebb941b0a04bff0f18769ac.