Add `bosh run errand [name]` cli command

Does not call BOSH Director yet

Signed-off-by: dmitriy kalinin <dmitriy@pivotallabs.com>
switch to using class method for logged-in-user shared example

Signed-off-by: dmitriy kalinin <dmitriy@pivotallabs.com>
require user to be logged in for bosh run errand

Signed-off-by: dmitriy kalinin <dmitriy@pivtotallabs.com>
added errands controller to bosh director api

/deployments/:dep_name/errands/:errand_name/run

Signed-off-by: dmitriy kalinin <dmitriy@pivotallabs.com>
Add run_errand message handler to bosh_agent

Signed-off-by: Johannes Petzold <jpetzold@pivotallabs.com>
formatting and use of instance_double in CompiledPackagesSpec

Signed-off-by: August Toman-Yih <atomanyih@pivotallabs.com>