Fixing upload_sha1 at end of push action

Commit 8532006 (pull request #141) broke uploading the SHA1 at the end
of the push action. That was fixed long time ago in the pull-feature
branch and covered by tests there.

This commit adds the missings tests and fixes the push action again. The
SHA1 is uploaded even if there are no other files to upload.
Merge remote-tracking branch 'git-ftp/develop' into develop

Conflicts:
	tests/git-ftp-test.sh