modify instances to add error message to body when the instance id does not match

Signed-off-by: Dave Liebreich <dliebreich@pivotallabs.com>
use instance_id from env var VCAP_APPLICATION, if available, as the instance id

Signed-off-by: Dave Liebreich <dliebreich@pivotallabs.com>
set rspec options

Signed-off-by: Dave Liebreich <dliebreich@pivotallabs.com>
Now can use sticky sessions

Signed-off-by: Dave Liebreich <dliebreich@pivotallabs.com>