Add CNAME file when we're ready to move over to the new domain

[tschaub]

Old example URLs will break unless we maintain the old structure - needs discussion.

[tschaub]

Currently, openlayers.github.io is redirecting to ol3js.org. This is what we eventually want, but ol3js.org is configured to redirect to www.ol3js.org - which we don't want. Removing CNAME (in 9fa92f4) should remove the redirect that GitHub provides. This may take some time to have any effect.

[ahocevar]

Having ol3/ in the path seems a bit redundant to me. But maybe the blog post that links to the examples can be updated to use the new urls?

[ahocevar]

Looking again, it seems there is nothing we need to do for now: Both paths work(http://openlayers.github.io/en/master/examples/ and http://openlayers.github.io/ol3/master/examples/) - it seems github serves both gh-pages and user.github.io.