#1070 Properties page: "Rule-Selection" should be disabled if project-local config is selected

[Ralf]

Reproduce:
1) Configure project-local rule-set and close the property-page and click OK.
2) Reopen the PMD property page.

Now the rule-selector at the lower part is active also "Use the ruleset configured in a project file" is selected.

When I switch to "Use local rules" and back to "Use ruleset ..." and the rule-selector is disabled.