tweak support-file output

move individual file output to debug level
add bytes-written

IPython/nbconvert/nbconvertapp.py

@@ -288,7 +288,7 b' class NbConvertApp(BaseIPythonApplication):'
             resources = {}
             resources['unique_key'] = notebook_name
             resources['output_files_dir'] = '%s_files' % notebook_name
-            self.log.debug("Writing extra files to %s", resources['output_files_dir'])
+            self.log.info("Support files will be in %s", os.path.join(resources['output_files_dir'], ''))
 
             # Try to export
             try:

IPython/nbconvert/writers/files.py

@@ -75,7 +75,7 b' class FilesWriter(WriterBase):'
                 self._makedir(path)
 
                 # Write file
-                self.log.info("Writing support file %s", dest)
+                self.log.debug("Writing %i bytes to support file %s", len(data), dest)
                 with io.open(dest, 'wb') as f:
                     f.write(data)
 
@@ -102,7 +102,7 b' class FilesWriter(WriterBase):'
                 dest = os.path.join(self.build_directory, dest)
 
             # Write conversion results.
-            self.log.info("Writing %s", dest)
+            self.log.info("Writing %i bytes to support file %s", len(output), dest)
             with io.open(dest, 'w') as f:
                 f.write(output)
             return dest
  No newline at end of file