Add hook script capability on droplet start/stop.

Hook script provide the CF providers to configure warden container based
on their demand. If providers want to start a special process for their purpose (*1)
in droplet container, they can setup it on container_root_fs (of Warden)
by chroot/apt-get combination and start the daemon by hook script.

(*1) e.g:

  - Log Collector daemon (flume, fluentd, ...etc),
  - Redis proxy daemon (Twemproxy to proxy requests to bound redis services)
  - ...

Change-Id: Ic4afc57a8d47b0797b93ce13c108d40a467dd091
Change 'stop' hooks timing since 'after_stop' does not make after warden container stopped...

The correct order is:

  RUNNING

  -> before_stop

  STOPPING

  -> after_stop

  STOPPED

Change-Id: I8aa3117e17ecb6da6bde412e83864f8ee366d9f1
added stop script test and refactoring of tests for script hooks.

Change-Id: If27105ccd50be09ba13580362588c11fbcf55d7f
bump java buildpack
Bump ruby buildpack

ruby buildpack shortlog 90d4896..3d0bd98
Elisabeth Hendrickson and Maria Shaldibina (1):
  Fix bundler path
Change Procfile and Raketask to start-up log-server properly
Add app_id to valid_staging_attributes
Extend timeout window for PortOpen healthcheck spec
In dev VM, don't put warden rootfs in /tmp
Optimize erlang cookbook

Bump erlang recipe so that it doesn't re-download erlang
if it's already present.

Cache file downloads outside of /tmp dir so they aren't
discarded on reboot
Remove log server from procfile

We haven't yet gotten logplex to compile correctly on travis.
Travis's workers have erlang installed, but it's an old version
that is incompatible with logplex.

Tests that integrate with the log server should start it up
separately.
Setup Vagrant port forwarding for logplex REST API.

This allows us to run integration tests that touch logplex from the Mac as well as within Vagrant.
Extract nats helper module for integration specs
Merge pull request #3 from yssk22/request/script-hooks

Add hook script capability on droplet start/stop.
Add initial staging integration test
Temporarily don't run tests that need warden on ci
Bump ruby buildpack

ruby buildpack shortlog:
Bleicke and Maria Shaldibina (1):
  Don't install libyaml
Use quotes instead of symbols to parse message in buildpacks
Update YAML parsing test
[fixes #45652433] Remove deprecated VMC env variables