seafile-ccnet: Update to 7.1.2, add Python 3 bindings package

seafile-ccnet: Update to 7.1.2, add Python 3 bindings package

* Update package to 7.1.2

* Add Python 3 bindings package. The Python dependency is moved from
  seafile-ccnet to python3-seafile-ccnet.

* Refresh patches. The path to valac does not need to be patched in
  010-Makefile.patch because $(STAGING_DIR_HOSTPKG)/bin is already in
  the path during package build.

* Use SEAFILE_UCI_LOG_DIR and SEAFILE_UCI_SOCKET_DIR, which will be
  added to seafile-server

* Install binaries to /usr/libexec instead of /usr/bin, to mirror an
  upcoming change in seafile-server

* Clean up Makefile formatting

* Add myself as a maintainer

Signed-off-by: Jeffery To <jeffery.to@gmail.com>