added PDO handling for databases [0.8.0]

This version introduces multiple enhancements:

added PDO handling for databases connection
also added possibility to log databases connection and queries

Details of additions/deletions below:
--------------------------------------------------------------

Added:      /Lib/Core/Db/Helper/Connection/Pdo.php
            -- Added --
                PDO connection library

Added:      /Lib/Core/Db/Helper/Connection/Interface.php
            -- Added --
                common interface for all connection libraries

Modified:   /Lib/Core/Db/Helper/Mysql.php
            -- Added --
                CONNECTION_MYSQLI constant
                CONNECTION_PDO constant
                $_connectionObject to store connection object
            -- Updated --
                $_options, added type option (connection library)
                __construct added handling of 2 type of connection libararies
                _query added handling of 2 type of connection libararies and queries log
                _setCharset added handling of 2 type of connection libararies

Modified:   /Lib/Core/Db/Helper/Abstract.php
            -- Added --
                logQuery to save all queries into log file

Modified:   /Lib/Core/Db/Helper/Connection/Mysql.php
            -- Added --
                interface to class
                logConnection to log connections
            -- Updated --
                $defaultCharset charset replaced by DEFAULT_CHARSET
                $_options, added documentation and charset replaced by DEFAULT_CHARSET
                __construct added handling of connections log

Modified:   /Lib/Core/Db/Model/Resource/Abstract.php
            -- Updated --
                _transformRowsToObject fixed giving parameter for Core_Blue_Model_Object in case if one parameter has key 'data'

Modified:   /Lib/Core/Db/Initialize.php
            -- Updated --
                init added possibility to connect by PDO
                _connectMysql renamed to _connect

Modified:   /Lib/Core/Db/etc/config.ini
            -- Added --
                some new configurations for log queries and connections
                pdo connections declarations
            -- Updated --
                changed version from 0.7.2 to 0.8.0

Modified:   /doc/events.md
            -- Added --
                new events for PDO connections