add redshift_connect_timeout
update Exception handling of Redshift
fix test. return 'conn.close rescue nil'
Merge branch 'kenjiskywalker-update_exception_of_redshift-and-add_redshift_timeout' into feature/support_connect_timeout
Update pg version to '~> 0.17.0'
Removed connection creation logic to check if host is reachable.
Because the existing code can catch the connection error.