use kt-paperclip, keep legacy projects somewhat alive

Author: will-r

Diff for: paperclip-av-transcoder.gemspec

@@ -25,6 +25,6 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "sqlite3"
   spec.add_development_dependency "coveralls"
 
-  spec.add_dependency "paperclip", ">=2.5.2"
+  spec.add_dependency "kt-paperclip", ">=6.0"
   spec.add_dependency "av", "~> 0.9.0"
 end