Remove det surgery

Notes:
* deploying this change will require some app downtime (probably several hours) as the `detection_extract_view_mv` needs to be re-built and re-indexed.
* this should fix #110 
It's just an alias. The device table stores tags and receivers. This hopefully make the query a little more readable.

> On 13 Nov 2014, at 11:22, David Nahodil <notifications@github.com> wrote:
> 
> In grails-app/conf/Config.groovy:
> 
> >  
> > -            left join surgery on detection_surgery.surgery_id = surgery.id
> > +            left join sensor on valid_detection.transmitter_id = sensor.transmitter_id
> > +            left join device tag on sensor.tag_id = tag.id
> ...
> left join device tag on sensor.tag_id = tag.id
> ...
> Is that right? there seems to be too many terms there, to me.
> 
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