Improve deployment of new homepage

[elsbrock]

We currently use a cronjob to look for new commits and then update dependencies and build the page. This is pretty error-prone and should be improved. Maybe we can even just copy the results from Travis CI over? Otherwise it may be a good idea to run our own CI (Jenkins?) and do it there.

[elsbrock]

So I was thinking about letting Travis handle the deployment.

Currently we actually build the homepage twice, once by Travis, once by premium. Instead, Travis could rsync the files over ssh to premium.

This would require giving access to rzl-homepage@premium. Bonus would be that we only deploy if master is green, leading to more stable builds. Objections?

[elsbrock]

Implemented in b113396

[elsbrock]

Hmm, it seems some files get lost:

https://travis-ci.org/raumzeitlabor/rzl-homepage/builds/49514455#L1176
https://travis-ci.org/raumzeitlabor/rzl-homepage/builds/49514455#L1176

Unsure why this is happening.

[elsbrock]

Fixed in 0e1cc21