Improve error handling

[EnriqCG]

Right now, there is very little error handling happening inside the module. I consider robust error handling a must to have this module in a production environment.

Here's a list of situations that must be correctly handled at run time. Feel free to post more in the comments.

• Asserted exchange/queue already exists with different settings
• Non-asserted exchange/queue does not exist
• Connection times out
• Connection with the AMQP host was lost
• getChannel() for a connectionName that does not exist

[EnriqCG]

Descoping this to the v1.1 Milestone.