Set default connection options to be compatable with redshift

If you try to connect to a redshift with the default configuration options, you get the following error:
```
Sequel::DatabaseConnectionError: PG::UndefinedObject: ERROR:
unrecognized configuration parameter "standard_conforming_strings"
```
If you pass in `{force_standard_strings: false}`, then you get:
```
Sequel::DatabaseConnectionError: PG::InsufficientPrivilege: ERROR:
permission denied to set parameter "client_min_messages" to "WARNING"
```
Required connection options shouldn't have to be passed, so change the defaults.