create dbvis_add_db_admin.rb

Dbvisulaizer offers a command line functionality to execute SQL pre-configured databases (With GUI).
The remote database can be accessed from the command line without the need to authenticate.
The module abuses this functionality to create an administrator in the database if DB user rights allow it.
Here's a TypeError bug when you do string concatenation (see why I said no string concatenation? :-) )

So this is currently how you call dbvisQuery:

```
sql = getSQL(dbType)
errors = dbvisQuery(dbvis,sql)
```

Your ```getSQL``` method could return nil. And then in ```dbvisQuery``` you'll concat that nil.... here's what happens if you concat nil in Ruby:

```
1.9.3p547 :001 > "blah" + nil + "blah"
TypeError: can't convert nil into String
```

So you need to check your return value. Or have your ```getSQL``` method return a string at all times.