* Marked server-side --secure-auth as a "zombie" option: can't set it to anything but 1. Throws a warning when used.
* Marked client-side --secure-auth option as a "zombie" option. Returns a deprecation warning when used.And returns an error is anything but 1 is specified.
* Removed mysql_old_passwords server plugin
* Removed mysql_old_passwords libmysql plugin
* old_passwords server side option does not allow setting to 1. So it's only 0 and 2
* Removed the OLD_PASSWORD() SQL function.
* Multiple internal special cases clean up from the server.
* Cleanup of the test cases testing old_password
* Update of the relevant test cases to cover the new functionality.
* Created a macro for the deprecation warning in the client tools. 
* Explictly marked --secure-auth as zombie in the help text too.
* Removed all the calls to mysql_options(MYSQL_SECURE_AUTH) from the client tools.
* Added a check to mysql_options(MYSQL_SECURE_AUTH) to generate an error if value is anything but 1
* Removed the SKIPSECUREAUTH mysqltest connection option.
* Cleaned up trailing space. 
* Removed references to old_plugin from scripts/