don't read user and site own ctags configurations when running unit tests

* --options=NONE is added to the command line of unit testing.

* stderr where warning messages are printed to is separately recored
  to a temporary file(STDERR.OUT) which is removed when the result of
  test case is successful.

This patch will fix an issue
(https://github.com/fishman/ctags/issues/75) reported by
Daniel Hahler.

Signed-off-by: Masatake YAMATO <yamato@redhat.com>