Use http_proxy to download release etc. when available

Signed-off-by: Jeffrey Peckham <peckham@pivotallabs.com>
Collapse UNIX into Linux in agent code

Signed-off-by: Tony Hansmann <thansmann@pivotallabs.com>
load is probably not the best idea
back-fill config_spec and platform_spec in agent
better wording
Platform is a module now

Signed-off-by: Tony Hansmann <thansmann@pivotallabs.com>
Introduce rspec-fire to bosh_agent

Signed-off-by: Jeffrey Peckham <peckham@pivotallabs.com>
improved test for Bosh::Agent:Platform

[#55682936]

Signed-off-by: Jeffrey Peckham <peckham@pivotallabs.com>