Refactor env spec.

[#61846226]

Signed-off-by: Tammer Saleh <tammer@pivotallabs.com>
Extract environment variable exporting behavior

Into new EnvExporter class.

[#61846226]

Signed-off-by: Tammer Saleh <tammer@pivotallabs.com>
Refactor exported env vars

Signed-off-by: Tammer Saleh <tammer@pivotallabs.com>
Fix env exporter spec to support ordering

Signed-off-by: Tammer Saleh <tammer@pivotallabs.com>
Add NullEnvExporter to Env spec

Remove testing of properly exported vars, since that's now covered by the EnvExporter

Signed-off-by: Tammer Saleh <tammer@pivotallabs.com>
Proper naming for starting/staging env

Signed-off-by: Tammer Saleh <tammer@pivotallabs.com>
Introduce EnvStrategyChooser

Signed-off-by: Tammer Saleh <tammer@pivotallabs.com>
Move env helper classes to namespace

Signed-off-by: Tammer Saleh <tammer@pivotallabs.com>
Fix incorrect use of instance_double

Signed-off-by: Tammer Saleh <tammer@pivotallabs.com>
DEA uses vcap_application from CC

[#61846226]

Signed-off-by: Tammer Saleh <tammer@pivotallabs.com>