init set config.py perms to 0600, otherwise warn user if config.py is not

Since config.py contains passwords in it, it should be protected as much as
possible.  At the very least, the file permissions should be 0600 to
restrict access to user that actually edits and runs 'fdroid' commands.

fdroidserver/init.py

@@ -109,6 +109,7 @@ def main():
         os.mkdir('repo')
         shutil.copy(os.path.join(examplesdir, 'fdroid-icon.png'), repodir)
         shutil.copyfile(os.path.join(examplesdir, 'config.sample.py'), 'config.py')
+        os.chmod('config.py', 0o0600)
     else:
         print('Looks like this is already an F-Droid repo, cowardly refusing to overwrite it...')
         sys.exit()