use 'errors' repository for defining cc errors

for adding/modifying errors, modify this repository. this makes it much
easier for ccng and client libraries (i.e. cfoundry) to stay in sync.
remove lower-level error definitions

merge VCAP::CloudController::Errors and VCAP::RestAPI::Errors into
VCAP::Errors

add VCAP::CloudController::Errors alias so everything doesnt have to
change
fix Error constant lookup to be scoped under VCAP
"make it work" - tim gunn
change InvalidAuthToken error code to 1000
Merge branch 'master' into error-normalization

Must add to cloudfoundry/errors:
["StackInvalid",   HTTP::BAD_REQUEST, 250001, "The stack is invalid: %s"],
["StackNameTaken", HTTP::BAD_REQUEST, 250002, "The stack name is taken: %s"],
["StackNotFound",  HTTP::NOT_FOUND,   250003, "The stack could not be found: %s"]

Conflicts:
	lib/cloud_controller/errors.rb
Update the errors to include the new Stack exceptions
Merge pull request #19 from cloudfoundry/error-normalization

Error normalization