invenio2-kickstart: customization for zenodo

* Specifies the name of the CFG_INVENIO2_REPOSITORY_GENERAL directory

* Checks for bower-base.json existence
I understand your point about the loss of consistency by doing this change, however keeping the repository and the package name equal here will imply some other changes in the script (eg. https://github.com/bouzlibop/invenio-devscripts/blob/zenodo-kickstart/invenio2-kickstart#L200 and https://github.com/bouzlibop/invenio-devscripts/blob/zenodo-kickstart/invenio2-kickstart#L246). And I'm not sure about any other places where there is an assumption that the general repository is located in `invenio` directory. Forcing the name here appeared to me the simplest and the most secure solution.