Link location to particular roasters for better traceability.

[kabalin]

With bean to farm traceability trend, we can start by linking location to roasters (location items with roaster tag). At this stage this can be just a field to select one or more from the list of existing roasters listed on EspressoLocator, then display them in location page. The roastery page will also contain a list of places they are supplying beans to.