Issue #7444 Clean up $modal code

- modify ModalHelpers.makeOnError so callback is invoked on $hide
- simplify response modal handlers
  - use ModalHelpers.makeOnError consistently
  - log non 202 responses as errors
  - remove 403 handlers as these are now handled globally
- add docco to PoolController.js
- rename helpers to signal they are external by capitalizing references
- add missing 304 interceptor helpers to pool-modify calls
- rename helper references to reflect their sources

Signed-off-by: Yan-Fa Li <yanfali@gmail.com>