fix(deis/client): `Exception.message` is deprecated for >= python2.7

Changes:
- use `Exception.args` tuple instead of `Exception.message`

Closes #2331
docs(installing_deis): import AWS provisioning docs
Merge pull request #2332 from kingcody/fix/exception-msg-deprecation

fix(deis/client): `Exception.message` is deprecated for >= python2.7
docs(installing_deis): refer to contrib/ec2
docs(README): add badge pointing to latest docs
style(README): change two badges' colors to match Deis logo
Merge pull request #2334 from bacongobbler/import-aws-docs

docs(installing_deis): import AWS provisioning documentation
Merge pull request #2337 from mboersma/add-docs-badge

docs(README): add badge pointing to latest docs
docs(testing): add better instructions for contributors
ref(docs): error on warnings for all Makefile targets