Add optional encoding parameter for current connection, default UTF-8

Set optional encoding parameter for the current database connection, defaults to UTF-8. In fact UTF-8 encoded databases will not display values correctly in a php application if this is not set explicitly.
Update mysql/ez_sql_mysql.php

Brought new encoding parameter to object initialization level so that user can decide, default is utf8.
Merge pull request #15 from Lwangaman/master

Add optional encoding parameter to the current database connection, default to UTF-8