Improve config settings for C3p0JdbcConnectionProvider

Suggestions for improving the the C3p0JdbcConnectionProvider config in subject.properties

1) The dbDriver param can be optional, since all standard drivers have already been loaded at startup. OR, if required, then check that it is defined in the config setup, before passing it on to the the driver load where it throws a NPE

2) If maxWait is set to <0 (as in the sources.xml example), it will default to wait 5 minutes for a connection. This is probably not what people want or expect. It should change the default or maybe output a warning or error

3) Implement other c3p0 settings. There are a number of c3p0 settings that aren't exposed by the subject api. The minPoolSize and initialPoolSize, for example, default to 3, which may not be what everyone wants.

I could be wrong about these, as I'm not a heavy jdbc user. This is just what it seems from looking at the source code.