Clarify droplet meaning

[#52290891]
periodically (as described by router.start) announce routes [#52096145]
Save temp file in binary mode (fix for Windows)

[Finishes #50910193], closes #27
move the 'droplet.health' log message so the dea logs a running app as RUNNING, not STARTING
greet the router on startup
stub greet_router
Use start_command in the win buildpack. Fixes in dea download.
Merge remote-tracking branch 'cf' into ironfoundry

Conflicts:
	lib/dea/staging_task.rb
	lib/dea/utils/download.rb