Upgrade to ember rc6

It seems that after the fixed required to upgrade to rc5,  the only thing remaining to fix for rc6 was the taxonomy toggle. So hopefully if this is all good we can close the pull request for rc5.

Changes for rc5:
  * added a call to super in species/taxonConceptRoute and trade/annualReportUploadRoute following the description of controller / model setup at http://emberjs.com/blog/2013/05/28/ember-1-0-rc4.html
  * changed the eachPart helper to use registerHelper rather than registerBoundHelper. You might want to verify the taxon concept pages (seem fine to me); also removed the foreach helper as I didn't see it used and potentially it could have the same problem

Changes for rc6:
  * changed the taxonomy toggle to extend Ember.View rather than LinkView

make sure to` rake tmp:clear`