Improve support for mysql 8

[bsutton]

This issue has been reported before but I'm hoping for a better solution rather than the previously offered work around.

When attempting to connect to a mysql 8 database the following error is reported:

MySQL Client Error: Authentication plugin not supported: caching_sha2_password

This is due to mysql changing the default authentication method to a more secure one.

Ideally this library would support this new method as the default method.

as a fall back it should be easy for a user to to configure galileo to connection to mysql 8 without having to reconfigure their database (which is some circumstances may be outside of their control).

The mysql connector offers the following:

cnx = mysql.connector.connect(user='lcherukuri', password='password',
host='127.0.0.1', database='test',
auth_plugin='mysql_native_password')

Note the additional connection parameter 'auth_plugin'.

It would be useful if this parameter could be passed to the galileo connection.
Mysql actually supports a number of other arguments so I wonder if we should simply allow a map of args to be passed.

[insinfo]

@bsutton
I've had little time to get involved in this, I'm very busy at work, if you want to read mysql documentation, study about it, implement and pull request (PR) I appreciate it.

[bsutton]

I'm in the same situation time wise at the moment.
For the moment I've reverted to MySQL 5.

Will try to look at this at some point if the future unless something else wants to jump in.

[mayur-16]

I also had same issue with mysql 8
and i followed this method to solve it. now its working fine.