use yajl everywhere

Change-Id: I90f454834f13022f2590fad98d2e4242f3ff008f
Flapping logic for missing instances

Refactor flapping logic. Reuse it for both crashed instances and
missing instances.

Change-Id: Ib2856a4bf7d5674582e47d60f2b67aa3b8ecf1ff
Merge "use yajl everywhere"
update vcap-common

source vcap-common from github, bump gem versions.

Change-Id: I44c2fd7065426fcba32d8dec13dfbf57ea0b3382
bump steno gem

Change-Id: I996ea9ef7e64d71109dcd1c9202c5ef60a687ad9
varz: missing_instances

Rename varz statistic named "down_instances" to the more appropriate
"missing_instances". This is also the name needed by dashboard app.

Improve test coverage for varz.

Change-Id: Ie42c9baac92ce4c5e72fa6b33b73e280d10f5b77
fix: do not publish expected vitals in case of error

a refactoring that cleans up the logic of releasing the varz as a step
separate from publishing. In case of error (e.g., bulk api provider
timeout), the varz that were reset to zero are no longer published for
collector to pick up.

Change-Id: Ic08c2a794504bdc5adb2def6aa65037c24d0c95c
Merge branch 'upstream/cf/master' into develop