chore(tests): update etcd to match CoreOS 402.2.0

https://github.com/coreos/etcd/releases/tag/v0.4.6
chore(docs): update Sphinx reqs and remove pexpect
fix(docs): silence header warnings and restore broken links
Merge pull request #1640 from mboersma/fix-sphinx-links

fix(docs): silence header warnings and restore broken links
Merge pull request #1638 from mboersma/update-etcd-tester

chore(tests): update etcd to match CoreOS 402.2.0
fix(controller): store limit fields on config

Having a separate "Limit" domain object was getting in our way, when
really it represents just an extension of a Config. This moves the
two JSON fields "cpu" and "memory" to Config and does away with Limit.
fix(controller): specify dicts as defaults and guard against old errors

We should have been initializing our JSONFields with dict objects, not
strings. Also upgrading from a slightly earlier version of Deis to this
change could hit a JSON encoding error, so catch that and use the chance
to clean up the data. Also reverted the unnecessary workaround of
subclassing JSONField.
docs(community): add policy on bounties
Merge pull request #1630 from mboersma/1613-limit-is-config

fix(controller): store limit fields on config
Merge pull request #1650 from gabrtv/bounty-policy

docs(community): add policy on open source bounties
chore(controller): update djangorestframework to 2.3.14

Several months of cleanup and bug fixes to a core Deis library:
https://github.com/tomchristie/django-rest-framework/compare/2.3.13...2.3.14