feat(slugbuilder): build without using a pipe for git archive

Ref #785
Ref deis/slugbuilder#9

This will break builds if the corresponding slugbuilder patch is not
merged first.
feat(client): add proxy support

Added proxy support via environment variables.
docs(using_deis): clean up proxy support
Merge pull request #1641 from deis/fix/builder/no-pipe

feat(slugbuilder): build without using a pipe for git archive
feat(controller): support for application key/value tags
feat(client): support for application key/value tags
chore(controller): fix south default values with a data migration
feat(tests): integration tests for tags, move limit tests under config
Merge pull request #1634 from carmstrong/client_proxy_support

feat(client): add proxy support
Merge pull request #1665 from gabrtv/tags

Application tags for scheduling to specific hosts
fix(*): all services ensure valid config file on reload

Closes #1099
Replaces #1626
test(builder): update etcd keys in builder test

The confd templates expected some more etcd keys than were seeded
before. Add those extra keys in.
fix(router): add check command for nginx config

Check for `<no value>` in nginx config, which usually means that
something is wrong with the configuration in etcd.
Merge pull request #1629 from deis/fix/check-config

fix(*): all services ensure valid config file on reload
fix(tests): take a nap after fleet restart
feat(*): add `make test-style` targets

This gives us an opporunity to run code checkers and linters as part
of testing, as we used to on travis-ci.org. By default, unit tests
will check code syntax and style first.
ref(*): clean up Go and Python code for `make test-style`
fix(docs): add client reference for `deis tags`
Merge pull request #1670 from mboersma/deis-tags-autodocs

fix(docs): add client reference for `deis tags`
Merge pull request #1666 from mboersma/1509-make-test-style

feat(*): add `make test-style` targets