Refactor XMLConfiguration to use Builder Pattern

[johnjaylward]

Fixes #541

What problem does this code solve?

Refactors the XML Configuration to use a builder pattern instead of public constructors with many parameters. This makes viewing the configuration easier to read and maintain.

Risks

The fields on the configuration have changed visibility from public to private and are now accessible via public getters. This means that a new release will not be a drop-in replacement and consumers of this library will need to correct code that is directly referencing those fields. This should hopefully be minimal impact as the fields were readonly (i.e. hopefully no one was actually using them).

Changes to the API?

Yes, public fields were marked private and constructors were deprecated. New methods were put in place for managing the XML Configuration.

Will this require a new release?

Yes

Should the documentation be updated?

I don't believe we have any documentation outside of the Java-docs referencing this API.

Does it break the unit tests?

No, but unit tests were updated to use the new API.

Was any code refactored in this commit?

Yes, as mentioned above.

Review status

APPROVED

[stleary]

Starting 3-day comment window.

[johnjaylward]

@stleary, would you mind using tags/labels to make it easier to see which PR are up for review and which are ready to commit? Not that we usually have a lot, but it may make it easier to see at a glance from the main PR screen.