Fix swift version requirement (#3)

* Modernize `Podfile`

* Fix swift version requirement

* Fix hardcoded podspec source tag

SimpleSource.podspec

@@ -1,16 +1,14 @@
 Pod::Spec.new do |s|
-  s.name                 = "SimpleSource"
-  s.version              = "1.0.0"
-  s.summary              = "Composable, easy to use data sources for UITableView and UICollectionView."
-  s.homepage             = "https://github.com/Squarespace/simple-source"
+  s.name                 = 'SimpleSource'
+  s.version              = '1.0.1'
+  s.summary              = 'Composable, easy to use data sources for UITableView and UICollectionView.'
+  s.homepage             = 'https://github.com/Squarespace/simple-source'
   s.license              = { :type => 'Apache', :file => 'LICENSE' }
-  s.authors              = { "Morten Heiberg" => "[email protected]", "Thor Frolich" => "[email protected]" }
+  s.authors              = { 'Morten Heiberg' => '[email protected]', 'Thor Frolich' => '[email protected]' }
   s.platform             = :ios, '9.0'
-  s.swift_version        = "4.2"
-  s.requires_arc         = true
-  s.source               = { :git => 'https://github.com/Squarespace/simple-source.git', :tag => '1.0.0' }
-  s.source_files         = "Sources/**/*.{h,m,swift}"
-  s.module_name          = "SimpleSource"
+  s.swift_version        = '4.0'
+  s.source               = { :git => 'https://github.com/Squarespace/simple-source.git', :tag => s.version }
+  s.source_files         = 'Sources/**/*.{h,m,swift}'
   s.dependency           'Dwifft', '0.7'
 
   s.test_spec 'Tests' do |test_spec|