Remove Bob Extension as dependency

Bob extension has to be removed. It is used at three places in this package :

• bob.pipelines/doc/conf.py

• To load the association list for the packages for intersphinx. We have to see if it is better to do the association between the package and their URL directly or any other solution.

• bob.pipelines/src/bob/pipelines/distributed/sge.py

• To load the rc configuration. This can be replaced by the exposed package

• bob.pipelines/src/bob/pipelines/datasets.py

• To list the files and folders inside a folder or a tarball and search for files either in a file structure or in a tarball.