Set pod spec's Swift version to 3.0 (#111)

BulletinBoard.podspec

@@ -19,4 +19,5 @@ Pod::Spec.new do |s|
   s.documentation_url = "https://alexaubry.github.io/BulletinBoard"
   s.module_name = "BLTNBoard"
   s.resources = "Resources/**/*.{lproj,png}"
+  s.swift_version = "3.0"
 end

README.md

@@ -25,7 +25,7 @@ Here are some screenshots showing what you can build with BulletinBoard:
 
 ## Demo
 
-A demo project is included in the `BulletinBoard` workspace. It demonstrates how to: 
+A demo project is included in the `BulletinBoard` workspace. It demonstrates how to:
 
 - integrate the library (setup, data flow)
 - create standard page cards
@@ -70,7 +70,7 @@ BulletinBoard is fully compatible with Objective-C.
 To import it in your Objective-C app, just add this line at the top of your files:
 
 ~~~objc
-@import BLTNBoard; 
+@import BLTNBoard;
 ~~~
 
 ## Usage
@@ -258,7 +258,7 @@ Several styles are available in the `BulletinBackgroundViewStyle` enum:
 
 ## Dismissal
 
-If you set the `isDismissable` property to `true`, the user will be able to dismiss the bulletin by tapping outside of the card or by swiping the card down. This property defaults to `true`. You should set this property to `false` if completing the task is required, and should not be avoided by the user. 
+If you set the `isDismissable` property to `true`, the user will be able to dismiss the bulletin by tapping outside of the card or by swiping the card down. This property defaults to `true`. You should set this property to `false` if completing the task is required, and should not be avoided by the user.
 
 By default, a close button will be displayed when the item can be dismissed. If you don't want this behavior, you can set the `requiresCloseButton` property to `false`. This is useful when the bulletin already provides an action button to close the item (such as a “Done“ button).