[ios] update pod spec & template

RNFirebase.podspec

@@ -6,7 +6,7 @@ Pod::Spec.new do |s|
   s.version             = package["version"]
   s.summary             = package["description"]
   s.description         = <<-DESC
-                            Wanna integrate firebase into your app using React Native?
+                            Integrate firebase into your app using the React Native SDKs.
                           DESC
   s.homepage            = "http://invertase.io"
   s.license             = package['license']
@@ -16,11 +16,4 @@ Pod::Spec.new do |s|
   s.platform            = :ios, "8.0"
   s.preserve_paths      = 'README.md', 'package.json', '*.js'
   s.source_files        = 'ios/RNFirebase/*.{h,m}'
-  s.dependency          'React'
-  s.dependency          'Firebase/Auth'
-  s.dependency          'Firebase/Core'
-  s.dependency          'Firebase/Database'
-  s.dependency          'Firebase/Messaging'
-  s.dependency          'Firebase/RemoteConfig'
-  s.dependency          'Firebase/Storage'
 end