Fix regex for finding pseudo-header position

The regular expression "^\\S<+$" attempts to assert that there are no
comment lines anywhere before end-of-buffer, but fails to do so.  The
following line is matched as a comment:

  # A line not beginning with a hash

Fix the regular expression.

Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
Merge pull request #18 from artagnon/commit-mode-fixes

Fix regexp