deposit: adaptation to new deposit assets block

* Changes webdeposit_assets block to deposit_js

Signed-off-by: Kamil Neczaj <kamil.neczaj@cern.ch>
base: fix for overwritting invenio's js

Signed-off-by: Kamil Neczaj <kamil.neczaj@cern.ch>
grunt: initial support of JSHint

* Uses JSHint to lint JavaScript under modules/.

Signed-off-by: Georgios Kokosioulis <georgios.kokosioulis@cern.ch>