Use Folly and RSocket from cocoapods (#379)

Summary:
I have released pods for Folly and RSocket on cocoapods. Thus we won't need to host different versions of these pods on our repository. I haven't removed those pods from `Specs` folder, as the current users of `0.16.2` would still be referring the Specs folder on the master branch. I will remove the specs folder once, all our pods are on cocoapods and we no longer need to host any pods.
Pull Request resolved: https://github.com/facebook/flipper/pull/379

Reviewed By: jknoxville

Differential Revision: D14185931

Pulled By: priteshrnandgaonkar

fbshipit-source-id: ea285024123e41c2d110827e26f79a72ef22c008

iOS/Podfile

@@ -11,10 +11,10 @@ target 'FlipperKit' do
   pod 'Flipper', :path => '../Flipper.podspec'
   # Pods for SonarKit
   pod 'PeerTalk', '~>0.0'
-  pod 'RSocket', '~>0.10'
+  pod 'Flipper-RSocket', '~>0.10'
   pod 'DoubleConversion', '~>1.1'
   pod 'glog', '~>0.3'
-  pod 'Folly', '~>1.0'
+  pod 'Flipper-Folly', '~>1.2'
   pod 'CocoaAsyncSocket', '~>7.6'
 
 end