Add host argument to get_connect_string()

'localhost' value used to be hardcoded in get_connect_string().
Now it's possible to pass a custom host name as a function argument.
Wrote test for this

Change-Id: I3ae9f1a7df0bb378da1210cd89eef3e5f203cf34
Make MySQL regexes generic across MySQL drivers

Note that mysqlconnector raises InternalError whereas mysqldb raises
OperationalError when a deadlock is found.  The reported error codes and
messages are identical, however.

Change-Id: Iac9167e0777e0bf4361bcf6a8722923cce052b90
Merge "Add host argument to get_connect_string()"