@js helper

[k2s]

related to https://github.com/linkedin/dustjs-helpers/issues/74

possible extensions to Dust core (which would of course change Dust far from logic-less):

• create functions from expressions to compiled version of template (performance improvement and easy debugging}
• add special Dust language element to eliminate need to wrap expressions to quotes {!if people.size()>10}many{:else}acceptable{/if} or {! "{" + moment(today).format('dd.MM.YYYY') + "}" }