localstore(feat): mirror state to local storage

[axtho]

depends on #102 to be done
before a fetch/ update/ insert effect check that we have a connection. If no connection warn user and only update the localstore (indexedDb). When we are online again, sync data (tricky).

Until then we will use localstorage for this (limit is 5mb data): using https://github.com/btroncone/ngrx-store-localstorage

[axtho]

closing in favour of #110 ... we'll wait for ngrx/db to be ported to v4