Swift 3 support (venmo#65)

* Update to Swift 3

* Bump version 0.4.0

* Rename HTTPURLResponse file too

* Prefer private over fileprivate

* Fix serializating HTTPURLResponse

* Don't say we failed if we didn't

* Swift 3.0.1

* tvOS target

* Swift 3.0.1

* Fix tvOS deployment target

* Fix upload tests

* Explicitly set SWIFT_VERSION

Without this, Xcode complains about the legacy Swift version not being
set.

* Remove explicit toolchain from CI

* Specify SDK for CI

* Add destinations for CI

...because Travis CI is so good.

* Use latest version of Xcode

* Clean up spacing

.travis.yml

@@ -1,15 +1,16 @@
 language: objective-c # lol
-osx_image: xcode8
+osx_image: xcode8.2
 xcode_project: DVR.xcodeproj
 
-script: xcodebuild -scheme "$TRAVIS_XCODE_SCHEME" test
+script: xcodebuild -scheme "$TRAVIS_XCODE_SCHEME" -sdk "$TRAVIS_XCODE_SDK" -destination "$DESTINATION" test
 
 matrix:
   include:
     - xcode_scheme: DVR-iOS
       xcode_sdk: iphonesimulator
+      env:
+        - DESTINATION="OS=10.1,name=iPhone 7 Plus"
     - xcode_scheme: DVR-OSX
       xcode_sdk: macosx
-
-env:
-  TOOLCHAINS=com.apple.dt.toolchain.Swift_2_3
+      env:
+        - DESTINATION="arch=x86_64"