Podspec: Add tvOS, watchOS support

Author: radex

SwiftyTimer.podspec

@@ -10,6 +10,8 @@ Pod::Spec.new do |s|
   s.requires_arc = true
   s.ios.deployment_target = '8.0'
   s.osx.deployment_target = '10.9'
+  s.tvos.deployment_target = '9.0'
+  s.watchos.deployment_target = '2.0'
 
   s.source_files = 'Sources/*.swift'
 end