non-manual ECO classes in GPAD export for production models

[cmungall]

from @tonysawfordebi :

- there are a number of annotations that use an ECO term that isn't a "... used in manual assertion" term. They are:
  > ECO:0005593    immunodetection assay evidence    
  cut -f 6 uniprotkb.gpad | grep ECO:0005593 | wc -l
  854

  > ECO:0000005    enzyme assay evidence
  cut -f 6 uniprotkb.gpad | grep ECO:0000005 | wc -l
  2

  > ECO:0000164    electrophysiology assay evidence
  cut -f 6 uniprotkb.gpad | grep ECO:0000164 | wc -l
  71