Get rid of build-time resource filtering

Right now we have a build-time username/password providing which means user can't change it after the war file was build and she'll be forced to unpack the app.
What we need is a runtime configuration of DB credentials so that user can change env var or tomcat var to change configuration.
In the future we'd like to configure tomcat itself on the server instead of unpacking the app. This is the first step to build a deployment pipeline.