provider: name length issue fix
provider: name length issue fix

* Fixes provider name to be less than 8 characters.

Signed-off-by: Lars Holm Nielsen <7eaffca9f7cd98839b5821d0d23e09ff764b82cd@cern.ch>

inveniosoftware/invenio-oaiserver,inveniosoftware/invenio-oaiserver