Fixes issue #34

When an invalid value is received as a version number an unsupported
version is raised instead of using the default/latest version number. A
few changes were required to implement this:

- A new exception was introduced in the ExtractionStrategy to
differentiate between no version being found and an invalid version
- A VersionedRequest will catch the strategy exceptions and log it as
an unsupported version
- A couple tests were fixed to expect the new result of an unsupported
version
- Some of the test fixtures were removed because they expected an
invalid result and there isn’t error verification on the fixtures tests