Add simplified Podspec (no support for codecs)

TwitterImagePipeline.podspec

@@ -0,0 +1,15 @@
+Pod::Spec.new do |s|
+  s.name             = 'TwitterImagePipeline'
+  s.version          = '2.25.2'
+  s.compiler_flags   = '-DTIP_PROJECT_VERSION=2.25'
+  s.summary          = 'Twitter Image Pipeline is a robust and performant image loading and caching framework for iOS'
+  s.description      = 'Twitter created a framework for image loading/caching in order to fulfill the numerous needs of Twitter for iOS including being fast, safe, modular and versatile.'
+  s.homepage         = 'https://github.com/twitter/ios-twitter-image-pipeline'
+  s.license          = { :type => 'Apache License, Version 2.0', :file => 'LICENSE' }
+  s.author           = { 'Twitter' => 'opensource@twitter.com' }
+  s.source           = { :git => 'https://github.com/twitter/ios-twitter-image-pipeline.git', :tag => s.version.to_s }
+  s.ios.deployment_target = '10.0'
+  s.swift_versions   = [ 5.0 ]
+  s.source_files = 'Sources/TwitterImagePipeline/**/*.{h,m}', 'Sources/TIPUtils/**/*.{h,m}'
+  s.public_header_files = 'Sources/TwitterImagePipeline/include/*.h'
+end