20 add option to trigger owl validation on load

[OwenR-York]

Housekeeping RDFModel

• Collected the property variables/methods together
  I added some comments to identify the sections/components more clearly.

RDFModel

• Add validation property (boolean) to RDFModel -- default on (true)
• Add accessor/mutator for the validation property
• Add property loading process for validation

RDFModelConfigurationDialog

• Add UI element (check box) to set the validation of models on load
• Add validation property storing process
• Add validation property recall process

There is only a check box for validation (on/off), this turns Jena's validation process on/off. Failing the Validation throws an exception which stops the loading process. In the future there may be a need for one or more validation processes a text box will replace the boolean check box, so a list (CSV) of validations can be given.

RDFModel

• Add validation method
• Capture validation errors with an EolModelLoadingException
• Insert validation method call into the load process

The existing method for validation could be replaced or overridden in future revisions to enable more complex validation techniques.

Test

• Add test to the OWLDemoData that runs validation to detect issues with MaxCardinality.

Added a new test file for testing validation. One test checks that the validation error message contains some expected string for the invalid OWL Data Model. The second test validates a corrected version of the OWL Data Model.

[Last revision] Change the internal property representation for validation to a text string, which can be used for a wider scope of validation processes.

• Change the property handling (internally) from boolean/string to only strings

[agarciadom]

The PR needs a bit more work before it can be merged. Specifically, I can't review RDFModel as there are too many changes which are unrelated to the main point of the PR. Please avoid making sweeping changes to a class unless the PR is specifically about it.