remove link to bitbucket from rtfd theme

[Reimar Bauer]

the edit link of read the docs to the bitbucket repository uses a wrong url. Also only maintainers could use that link.

A hint is given at http://stackoverflow.com/questions/36019670/removing-the-edit-on-github-link-when-using-read-the-docs-sphinx-with-readthed

[Reimar Bauer]

only the main page has that Edit link left over.

[Reimar Bauer]

was fixed with changeset #badf5de