Added smoke_tests errand

- Added src/smoke-tests submodule
- Added warden smoke_tests properties
- Run with: `bosh run errand smoke_tests_z1`

[#70397660]

Signed-off-by: David Varvel <dvarvel@pivotallabs.com>
Changed errand names to remove zone indicator.

- Only one errand can ever be run at a time

[#70397660]

Signed-off-by: David Varvel <dvarvel@pivotallabs.com>
Created a resource pool for errands

[#70397660]

Signed-off-by: David Varvel <dvarvel@pivotallabs.com>