implement docs pipeline changes in ci scripts

These changes implement the plan decided upon in #2 (closed). The docs will be hosted from our webserver with versioning support.

gitlab/after_docs.sh

 #!/usr/bin/env bash
 # Thu 22 Sep 2016 18:23:57 CEST
+
+# unset vars exported in before_docs.sh
+unset IS_MASTER
+unset MASTER_UPLOAD_PATH
+unset TAG_UPLOAD_PATH
+unset STABLE_UPLOAD_PATH