Doppler now does the syslog stuff

Signed-off-by: Trevor Ackerman <tackerman@pivotal.io>
Ignore blank syslog_drain_url for the syslog_drain_urls endpoint

[#79293594]
Lock the app when performing a restage

[#79658946]
Buildpack bits should use nginx when downloading

[#80080142]
/v2/syslog_drain_urls no longer returns nil or empty strings

[#79293594]
bulk endpoints should respect diego cc configuration

[#79973812]

Signed-off-by: Johannes Petzold <jpetzold@pivotal.io>
Updated valid deigo config options
Add drain for restarts due to memory usage

* restart_drain unregisters cc route, kills nginx gracefully but hard
  timeout after 30 secs, and then kills cc

* relies on monit to restart cc after we kill it

[#79416982]
Fix race condition when figuring out positions for buildpacks.

- Creates a locking table for full table locks

[#80149038]
internal endpoints use InternalApi auth instead of BulkApi