introducting syncMode

introducing syncMode, this rootScope variable is used to `force` the db
engine to fetch from the local db

if syncMode is true, dbEngine will fetch from the local db even if
there's a connection with the server

PS:
syncMode by default is set to false, only when called from the
syncEngine it should be set to true and set back to false after we're
done with it
syncMode introduced

- using syncmode we can *forcefully* tell dbEngine to fetch from the
local db
syncEngine2 looks good

- only proof reading remains!
API url