#46 RuntimeJavaFileManager updates for Java 9+.

• Re-enable runtime Java compiler tests for JDK compiler.
• Override 'contains' method introduced in Java 9.
• Using the ECJ compiler provided by JDT still fails.
  • It requires this fix.
  • It also requires JDT patch I created.
    • See https://bugs.eclipse.org/bugs/show_bug.cgi?id=541269.
  • With the 2 fixes combined, all our unit tests work.

Addresses #46 (closed)