Fix ambiguous resolution with react-native module (#266)

Picker.podspec

@@ -14,8 +14,6 @@ Pod::Spec.new do |s|
   s.platform       = :ios, '7.0'
   s.preserve_paths = '*.js'
 
-  s.dependency 'React'
-
   s.subspec 'Core' do |ss|
     ss.source_files = 'ios/RCTBEEPickerManager/*.{h,m}'
     ss.public_header_files = ['ios/RCTBEEPickerManager/*.h']