Fixes #95, Add dead letter example

[lpender]

This is adapted and generalized from working code but has not been tested in its adapted version. Please check for errors if possible. If not I'm sure we'll hear about them from the community :)

Not sure if this is the best place for it but it seemed like it due to the recent mention of dead letter exchanges

[coveralls]

Pull Request Test Coverage Report for Build 1806f2d4dcd1ef336edbf318c0f5325c7de7fffb-PR-100

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 76.0%

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Totals
Change from base Build 5f48634eaaa814e2339d491e2c6579510bde80f5:	0.0%
Covered Lines:	133
Relevant Lines:	175

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💛 - Coveralls

[josevalim]

@whatyouhide if you can do a double check it will be very appreciated! :heart:

[whatyouhide]

@lpender I took the liberty to go ahead and commit most of your code plus the fixes we discussed directly. Thanks a lot for the contribution! 💟

[lpender]

ok thank you!