Introduce a git_get_file_or_project_config utility function to
retrieve a repository variable either from a plain text file in the
$GIT_DIR or else from 'gitweb.$variable' in the repository config
(e.g. 'description').
This would be used in next commit to retrieve category for a project,
which is to be stored in the same way as project description.
Signed-off-by: Sebastien Cevey <seb@cine7.net> Signed-off-by: Jakub Narebski <jnareb@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>