Xcode 7 support

[czechboy0]

Xcode Server that shipped with Xcode 7 breaks Buildasaur, because the API version has been upped.

Back to reverse engineering.

[czechboy0]

The basics are working, Xcode Server just now uses Nginx listening on port 20543 and the path changed from /xcode/api to /xcode/internal/api. Now I'm seeing issues with SSL fingerprint validation, investigating that now.

[czechboy0]

Progress on branch experimental_xcode7_support.

[czechboy0]

Okay, I think I have assessed the damage. The blueprint remote repository dictionary added values for fingerprint validation, which we need to add. Also the way that devices to test on are specified has changed slightly. Having an experimental version that works with Xcode 7 should not be too much work, but careful considerations need to be taken in order to properly support both versions 2 and 3 with Buildasaur. (The version number gets passed in the headers from every XCS response)

[czechboy0]

Actually, some of this work will be done with #71. But the fingerprint validation still needs to be fixed here.

[czechboy0]

Ok, #71 migrated to XcodeServerSDK. So now it's down to just the fingerprint validation and we should be good to go.

[czechboy0]

Work going on: https://github.com/czechboy0/XcodeServerSDK/labels/xcode7-compatibility

[czechboy0]

Waiting for #77 and UI fixes with migration to the new XcodeServerSDK 0.1 (with Xcode 7 Server API support).

[czechboy0]

Ok got it working. Just had to disable SSH key validation, but that will be brought back in #79.