Ignore fewer tests

This pull request:
(a)
      adds equality testing to OntologyIDTestCase .
      tests equality and hashcodes for IDs with versionId set. 
      Fixes  ignored test (test would fail because ontology IDs with different versions, which presumably ought to differ, were being expected to be equals.) 
  (    If OntologyIDs with different versions should be Object::equals then the newer tests are wrong, as is the code).  
(b) Sets temporary files in TutorialSnippets to be deleted on exit. -
http://docs.oracle.com/javase/7/docs/api/java/io/File.html#deleteOnExit()
 The files can be left behind  iff the JVM is terminated so abnormally as to bypass Java shutdown hooks. - http://docs.oracle.com/javase/7/docs/api/java/lang/Runtime.html#addShutdownHook(java.lang.Thread)

(there's an unrelated commit that adds some intellij project patterns  to the root .gitignore )