[meta] Fix broken deploy story, redux

[anssiko]

[This is a meta issue only the spec editors should care about.]

Travis-based deploy has been giving false negatives and failed to build properly (deployed a text file that contains just bogus bikeshed error message instead of the generated HTML), so I suggested to the editors we move to the good ol' workflow where we generate the index.html locally and commit it together with the corresponding index.bs source.

As an interim solution, I switched the repo to serve https://w3c.github.io/sensors/ from the master branch, and @pozdnyakov added a generated index.html to the same branch.

TODOs:

• disable deploy.sh in travis.yml
• remove unused deploy.sh script and any related config files from the master branch