Better Healthcheck Testing/Blank dbname/user Testing

[reynoldsalec]

We just implemented a fix to handle situations where the user specifies blank dbname/password/username for the db config. Ex:

services:
  database:
    type: mysql
      creds:
        user: customusername
        password:
        database: customdbname

The fix: b78401f

I put in a "test case" in the custom example to make sure a blank password wouldn't fail the healthcheck or otherwise create problems, however, I'm not testing blank user or database values. From some quick manual testing it looked like those worked ok, but would be good to explicitly test this.