ISIS-421: working on RO TCK tests.
ISIS-421: more work on RO TCK tests
Reformatting EnumValueSemanticsProvider...

... apparent glitch in git with line endings?
ISIS-421: fixes to in-memory objectstore to make RO TCK tests more reliable...

... key on ObjectSpecId not on ObjectSpecification, since the latter can sometimes be discarded.

Specifically, this was occurring as a result of a prior test which attempted to get a non-existent property (returning a 404); as a side-effect the ObjectSpec was discarded, meaning subsequent tests could find no instances of the class.

In addition
- extended IsisWebServerRule to allow webapp to be discarded (after mutating change)
- copied in boilerplate for all "TODO" tests that are likely to mutate state (and so will need to use this new "discardWebApp()" functionality).