Merge pull request #1212 from mxcl/swift/3.1

[oh] we no longer support Swift 3.1

Author: mxcl

Documentation/Installation.md

@@ -88,13 +88,13 @@ PromiseKit contains Swift, so there have been rev-lock issues with Xcode:
 
 | PromiseKit | Swift                   | Xcode    |   CI Status  |   Release Notes   |
 | ---------- | ----------------------- | -------- | ------------ | ----------------- |
-|      6     | 3.1, 3.2, 3.3, 4.x, 5.x | 8.3, 9.x, 10.x | ![ci-master] | [2018/02][news-6] |
+|      6     |      3.2, 3.3, 4.x, 5.x | 8.3, 9.x, 10.x | ![ci-master] | [2018/02][news-6] |
 |      5     | 3.1, 3.2, 3.3, 4.x      | 8.3, 9.x, 10.1 | *Deprecated* |       *n/a*       |
 |      4     | 3.0, 3.1, 3.2, 3.3, 4.x | 8.x, 9.x, 10.1 | ![ci-master] | [2016/09][news-4] |
 |      3     | 2.x                     | 7.x, 8.0 | ![ci-swift2] | [2015/10][news-3] |
 |      2     | 1.x                     | 7.x      | *Deprecated* | [2015/10][news-3] |
 |      1†    | *N/A*                   | *        | ![ci-legacy] |         –         |
-                                     
+
 † PromiseKit 1 is pure Objective-C and thus can be used with any Xcode, it is
 also your only choice if you need to support iOS 7 or below.
 
@@ -152,7 +152,7 @@ extension) then all your final products that use PromiseKit will have forced
 dependencies on all the Apple frameworks that PromiseKit provides extensions
 for.
 
-This isn’t that bad, but every framework that loads entails overhead and 
+This isn’t that bad, but every framework that loads entails overhead and
 lengthens startup time.
 
 It’s both better and worse with Carthage. We build individual micro-frameworks

PromiseKit.podspec

@@ -19,7 +19,7 @@ Pod::Spec.new do |s|
   s.default_subspecs = 'CorePromise', 'UIKit', 'Foundation'
   s.requires_arc = true
 
-  s.swift_versions = ['3.1', '3.2', '3.3', '3.4', '4.0', '4.1', '4.2', '4.3', '4.4', '5.0', '5.1', '5.2', '5.3', '5.4']
+  s.swift_versions = ['3.2', '3.3', '3.4', '4.0', '4.1', '4.2', '4.3', '4.4', '5.0', '5.1', '5.2', '5.3', '5.4']
 
   # CocoaPods requires us to specify the root deployment targets
   # even though for us it is nonsense. Our root spec has no