move context inside runner -- integration tests still passing, nothing else even checked
fix context package tests
fix uniter/operation tests
rename uniter/context to uniter/runner
Merge branch 'master' into uniter-deemphasise-context
Merge pull request #1231 from fwereade/uniter-deemphasise-context

uniter/context: move context inside runner


   * Renamed uniter/context to uniter/runner
   * runner.Factory now creates runner.Runners (rather than context.Factory creating context.Contexts)
   * loads of consequent test changes
   * loads of tedious renames


(Review request: http://reviews.vapour.ws/r/541/)