pidstore: name conflict fix
pidstore: name conflict fix

* Fixes a name conflict between a class defined in the file
  and a class imported in the same file.

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

inveniosoftware/invenio,tiborsimko/invenio,tiborsimko/invenio,inveniosoftware/invenio