Proxy/server fixes.

* Avoid null pointer exception when proxy URL has no host.
* Add better MIME types for several file extensions.
Load json in a beforeAll so it only runs when the specs run.
Avoid use of real, resolvable hosts in tests.

such as "fake.net" and "up.com".  Instead use the ".invalid" TLD which is reserved.
Merge pull request #849 from AnalyticalGraphicsInc/fixProxy

Proxy/server fixes.
Merge pull request #850 from AnalyticalGraphicsInc/fixHostsInSpecs

Avoid use of real, resolvable hosts in tests.
Merge branch 'master' into viewer
Update CHANGES
Merge branch 'viewer' into viewer-mixins