invenio2-kickstart: customization for zenodo

* Specifies the name of the CFG_INVENIO2_REPOSITORY_GENERAL directory

* Checks for bower-base.json existence
> ASSETS_DEBUG=True the build assets are just ignore thus you 'only' loose a bit of time

OK.


> Or the .travis.yml and kickstarter could use a common script.

That's indeed how we've been doing it in the Invenio 1.x world:

- https://github.com/inveniosoftware/invenio/blob/master/.travis.yml

(e.g. Jenkins builders use the same as well)