Update TODO list on README.md

[ci skip]
Update to Elixir v0.13.1

* Update JSEX (decode to maps)
* Use Dict instead of ListDict
* Use maps instead of list dicts
Update README.md

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Use signaturex to validate requests
Use 600 seconds as timestamp grace

[ci skip]
Update README.md

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Add last release version badge

[ci skip]
Add support to 0.13.2
Update signaturex

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Update comprehensions to for comp.
Update "Deploying on Heroku" section on README.md

[ci skip]
Update README.md

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Add Lifetime to disconnection on Console
Use exrm instead of relex

[ci skip]
Move signaturex to included_applications

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Update Release section on README.md

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Bump version 0.1.1

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Update exlager
Update to Elixir 0.13.3