moved action validation into context package; context tests not yet fixed
tests WIP
merge parent, resolve conflicts
merge imminent future parent, fix conflicts
beef up tests
Merge branch 'uniter-context-export-flush' into uniter-action-context-2
finally fix crazy tests in not-very-happy-making way
Merge branch 'master' into uniter-action-context-2
drop redundant runner code
address review
ok, fine, I'll handle those api errors, even though I'm pretty sure we *shouldn't* be getting them in the sometimes-failing uniter test
Merge branch 'master' into uniter-action-context-2
update the tests that check the details of the dummy charm actions
Merge pull request #1102 from fwereade/uniter-action-context-2

uniter: move action validation into context factory

Main benefit:
  * untangled much of the ugliness/confusion in uniter.runHook
  * added unit tests for action notfound/unauth

Driveby improvement:
  * uniter no longer takes the execution lock until it's got a valid context to run in