Use zowe.yaml as the source for the configuration

[achmelo]

Is your feature request related to a problem? Please describe.
Users should have a more standardized way to configure all the components and should not rely on additional environment variables.

The variables used across the API Mediation Layer should be derived from the zowe.yaml instead of depending on environment variables or on provision of the variables through start.sh

Describe the solution you'd like

• Standardizing what goes into start.sh and what is kept out and updating start.sh accordingly

[pinpan]

Intro
APIML configuration is based on application.yaml files. The values of the properties can be provided externally to reflect environment or system specifics not known at component packaging time. The values are supplied by system properties set on the command line constructed by the start.sh script for the respective component.

Problem to solve:
We need to review individual properties and parameterize them where is needed to make them externalizable.

Suitable defaults should be provided in the component's application.yaml. The properties for the component configuration properties are currently set in the zowe.yaml or by environment variables (from PARMLIB/s). In the future with the help of the ConfigManager, properties' values would be provided also by component-specific YAML files which will be merged to the zowe,.yaml. In order to ensure that the values will be valid, we need to provide a validation schema per component.