Fix the fails() by repurposing it as an assertion
Merge pull request #76 from wikimedia/fails-fails

Fix the fails() by repurposing it as an assertion
Improve metric handling for HTTPErrors
Depend on preq 0.2.11

Tests were failing with 0.2.10, as that wasn't returning instances of the
global Promise object.
Convert 'deleted' attributes into a tag set

We need to express various restrictions of a revision, including 'deleted' and
'suppressed'. A simple way to do so is via a set of string tags. This patch
removes the old boolean 'deleted', and replaces it with a set of strings.