Fix repo name in Podfile (#1528)

Summary:
A few people reported issues due to the previous repo name (`Sonar`) being referenced in the Podfile.

- https://github.com/facebook/react-native/issues/27565
- https://github.com/facebook/react-native/issues/29251
- https://github.com/facebook/flipper/issues/1321

This PR updates it to the current name (`flipper`). Please let me know if these updates are also needed for the files under `Specs/Flipper/**/Flipper.podspec` (not sure what the purpose is).

Pull Request resolved: https://github.com/facebook/flipper/pull/1528

Reviewed By: nikoant

Differential Revision: D23730546

Pulled By: passy

fbshipit-source-id: b4d776f44a054f3fe8b793ca36a8fbc8835e5d04

FlipperKit.podspec

@@ -10,11 +10,11 @@ Pod::Spec.new do |spec|
   spec.name = 'FlipperKit'
   spec.version = flipperkit_version
   spec.license = { :type => 'MIT' }
-  spec.homepage = 'https://github.com/facebook/Sonar'
+  spec.homepage = 'https://github.com/facebook/flipper'
   spec.summary = 'Sonar iOS podspec'
   spec.authors = 'Facebook'
   spec.static_framework = true
-  spec.source = { :git => 'https://github.com/facebook/Sonar.git',
+  spec.source = { :git => 'https://github.com/facebook/flipper.git',
                   :tag=> "v"+flipperkit_version }
   spec.module_name = 'FlipperKit'
   spec.platforms = { :ios => "9.0" }