mail using spring boot's starter

Merge pull request #59 from spinnaker/more-mail-properties

use spring boot mail starter instead of java mail directly.

Echo 1.78.0

updated scheduled-actions dependency to return human-readable description of validated cron expression

Echo 1.77.0

Dependency update including kork-cassandra init fix

fix echo event flattening

Merge pull request #56 from spinnaker/fix-event-flattening

events were being incorrectly flattened for all events

allow optional rest event flattening

Merge pull request #55 from spinnaker/flatten-details-to-strings

allow details to be flattened to json string to facilitate downstream processing

correctly send out events for failed pipelines

Merge pull request #53 from spinnaker/fix-canceled-check

change in orca means we cannot rely anymore on the canceled flag

fix echo event wrapping

Merge pull request #47 from spinnaker/fix-log-message

rest service logging is not showing request URL

remove time-series polling

allow multiple REST endpoints