Pass missing old sections to refresh method. Remove deprecated .swift-version.

Author: colinhumber

.swift-version

@@ -9,6 +9,7 @@ Pod::Spec.new do |spec|
   spec.author = { 'Venmo' => 'ios@venmo.com', 'Sam Soffes' => 'sam@soff.es' }
 
   spec.platform = :ios, '8.0'
+  spec.swift_version = '4.2'
   spec.frameworks = 'UIKit'
   spec.source_files = 'Static/*.{swift,h}'
 end

Static.podspec

@@ -28,7 +28,7 @@ public class DataSource: NSObject {
     public var sections: [Section] {
         didSet {
             assert(Thread.isMainThread, "You must access Static.DataSource from the main thread.")
-            refresh()
+            refresh(oldSections: oldValue)
         }
     }
 
@@ -101,8 +101,8 @@ public class DataSource: NSObject {
         refresh()
     }
 
-    private func refresh() {
-        refreshTableSections()
+    private func refresh(oldSections: [Section]? = nil) {
+        refreshTableSections(oldSections: oldSections)
         refreshRegisteredCells()
     }