extract_messges seems can not ignore hidden files #471

Say I have a folder contains some template file:

templates/
  .some.html
  .#other.html
  layout.html

what I want is to ignore the hidden files and only parse the layout.html. But what Babel does seems to be:

1. get all the directory and files under some directory
2. match the filename with the pattern defined in mapping_file

The second step does not take the hidden file into consideration.
And the mapping_file seems does not support the glob pattern like : [!#]*.html or [a-z]*.html.
I think use the built-in glob module of python will be better.