Rename Remote::FS#{has_,}file?

lib/producer/core/remote/fs.rb

@@ -12,7 +12,7 @@ module Producer
           @sftp ||= @remote.session.sftp.connect
         end
 
-        def has_file?(path)
+        def file?(path)
           sftp.stat!(path).file?
         rescue Net::SFTP::StatusException
           false

lib/producer/core/tests/has_file.rb

@@ -3,7 +3,7 @@ module Producer
     module Tests
       class HasFile < Test
         def verify
-          env.remote.fs.has_file? arguments.first
+          env.remote.fs.file? arguments.first
         end
       end
     end