Release 20160426 (convox#584)

* Handle environment section in map format

fixes #112

this pulls in some code from libcompose (Apache license) but modifies it to work with gopkg.in/yaml.v2.

* sub underscores for hyphens

* use underscores for env vars in deployed apps, too

* fix check for proxy locally

Merge pull request convox#575 from convox/release-20160425

Release 20160425

Merge pull request convox#564 from convox/release-20160420

Release: 2016-04-20

Merge pull request convox#541 from convox/docker-logs-tail

Logs Delivery and Tail Reliability

Merge pull request convox#549 from convox/ci-install

install from template in S3 assuming VERSION build parameter is set

Merge pull request convox#545 from convox/proxy-labels

ProxyProtocol fix

Merge pull request convox#539 from convox/godep

Go 1.6 and Godep vendor/

Merge pull request convox#535 from convox/build-enhancements

Build enhancements

Merge pull request convox#530 from convox/build-plus-plus

convox#507 Build Provider Refactor
convox#496 warn if app contains unignored env
convox#514 don't panic on malformed labels
convox#529 Add support for passing existing IAM/ACM arn to convox ssl create/update commands
convox#526 run specific release

getting the wrong callback host in production