Update Registration.php

Replace mysqli functions by PHP PDO functions in all database calls.

Replace all direct calls to "new mysqli(DB_HOST, DB_USER, DB_PASS, DB_NAME)" by the function "private function databaseConnection()"
This function check if database connection already opened, create connection if needed and return true or false (if false, error message is added to error string of the class)
live demos email notice
notice about REAL email adress in the views
removed unnecessary html code from verification mail
[#159] captcha form field is now mandatory (clienside via HTML5 attribute)
gmail problems guideline
gmail problems guideline
correct config file paths in readme
donation changed from "$10" to "some dollars"
better guide on how to chmod the avatar folder
more info on gmail.com issues
[#165] better email links
important slash notice
mail sending in live demos works again
[#138] rewritten cookie login ! the entire cookie actions is now done by controller/action/model, exactly like it should be ;)
Merge remote-tracking branch 'origin/develop' into develop
removed annoying and unnecessary avatar file writeable file (only the folder needs to be checked)
changes August 20th 2013
[#167] route user to last visited page after re-login with cookie
[#167] route user to last visited page after re-login with cookie