New table mysql_hostgroup_attributes

[renecannao]

MySQL Hostgroups could have generic attributes to apply to all connections to that specific hostgroup (no matter the specific host), while right now they can only be set either globally of per query. Therefore there is the need to create a new table to define hostgroup attributes. Some variables to start with:

• [ ] mysql-enforce_autocommit_on_reads
• [ ] mysql-free_connections_pct
• [ ] mysql-init_connect
• [ ] mysql-multiplexing
• [ ] mysql-query_retries_on_failure
• [ ] mysql-shun_on_failures
• [ ] mysql-shun_recovery_time_sec

[renecannao]

Incorrectly referenced commits for #995 in #955