change DEA evacuation bail out time to 6 minutes
remove legacy directory server

[finishes #61846108]

Signed-off-by: Ruth Byers <rbyers@pivotallabs.com>
added integration test for deterministic evacuation
Register with the router while the instance is evacuating
bump evacuation timeout to 10 minutes
Ensure %CPU is available when disk quota disabled

The stat_collector task coded with the expectation that disk statistics
would always be available but when disk quotas are not enabled for
warden, the statistics are not populated and the collector would take an
exception dereferencing the nil message.  That exception would prevent
cpu statistics code from executing resulting in cpu data always
returning 0%.

This adds a check for nil on the disk usage assignment.
enforce schema in dea.advertise message
Removed unused reference to loggregator
Separate staging and app logs by prefix

Use "STG" prefix in staging log tag and "APP" prefix in application
running log tag.
Use redirect instead of pipe to fix buffering issue