Introduce a `production` profile to use a JNDI datasource instead of the datasource instantiated by the .war application.

Hello, I discussed the ideas of this pull request with @jhoeller at GeekOut; Juergen did not see the code.

The purpose of this change is to allow to deploy Spring PetClinic on a tomcat-mysql environment without any code change, just overriding few configuration parameters with system properties (see sample at http://petclinic.examples.cloudbees.net/ ).

Details:

1. Associate the JDBC repositories implementation with the `default` profile in addition to the existing association with the `jdbc` profile -> file business-config.xml,
1. Remove the `spring.profiles.active` web context-param to allow overriding of the application's profile by a system property; unless overridden by a system property `spring.profiles.active`, the web app uses the profile `default` -> file web.xml,
1. Allow to override values of `data-access.properties` with system properties (`<context:property-placeholder ... system-properties-mode="OVERRIDE"/>`) -> files business-config.xml and datasource-config.xml,
1. Introduce a `production` profile to use the JNDI datasource instead of the embedded datasource -> file datasource-config.xml