Provide standard, documented and more clear error messages

Summary
=======
Horizon serves well as the first point of contact for new users to OpenStack, and it's well-known that operating and troubleshooting this cloud system can be difficult, specially for new adopters.
The ultimate goal of this proposal is to bring an enterprise-class User Interface that helps admin and non-adminusers to find their way when they encounter an error in Horizon, providing
helpful messages, providing info about endpoints originating the error and links to documentation that further describe the possible solutions and troubleshooting for the error.

The goal here is to handle what is in Horizon's scope and provide enough details so the operator can reach to the next level of support with more than just a "Could not create image"

Motivation
========

Warning and Error messages in horizon are unclear and do not provide any useful information to operators other than "Could not create image", etc. Horizon should take care of the erros more gracefully, meaning that
it should provide a better description of the error, and a link/code to a knowledge base of common erros that wiil provde the operator more details about the error and who to troubleshoot it from the horizon perspective

The errors related to API calls are currently poorly handled and they lack of enough information for the operator to quickly troubleshoot issues

Description
=========
This effort will involve lots documentation. We need to give error codes to any potential API call that could posibly result in an error, if possible separating them by service, i.e.:
N001 (where "N" means nova and the number an specific known error)
Q200 (where "Q" is neutron service)
C150 (where "C" is cinder service)
etc.

The alert widget should be improved in such way we can include a link to the "known error code"

A Wiki with all the error knowledge base should be created and documented

UX
===
Some error messages could
Depending of the type of user:
  - API service and hostname/ip address/port (Admin only)
  - Precise timestamps
  - HTTP Status Codes (Admin Only)
  - API Version (Admin ONly)
  - Original message from the API
  - Links to central knowledge database /documentation/ etc
  - Send an email to Cloud Admins or any other email address configured in localconf, with the content above (Configurable)

Outside Dependencies
==================
Translations of error messages: Each service must provide translations for its error/warning messages (in an ideal world)

We should be able to accomplish this without having the need to ask for modifications in error messages
Need a wiki where we can build the knowledge base

Requirements Update Required
========================

Doc Impact
=========

Change the alert messages default behavior
Create wiki for kowledge base documentation
Add a release note
Document link to the wiki