installation: version compare >= by default
jsonalchemy: JSON search addition

Signed-off-by: Adrian-Tudor Panescu <adrian.tudor.panescu@cern.ch>
JsonAlchemy: namespaces added WIP

* Remove invenio/core

* Remove invenio/legacy/bibfield
Merge pull request #178 from egabancho/pu-jsonalchemy

JsonAlchemy: namespaces added WIP
Merge pull request #175 from adrianp/poo

JSONAlchemy: JSON search addition
translations: fixes for string formatting
translations: fixes for trailing whitespace