docs(deisctl): reword comment
fix(tests): Allow TLS

Fixes https://github.com/deis/deis/issues/2230
docs(installing_deis): import baremetal docs
docs(contrib): refer to digitalocean guide
docs(testing): add better instructions for contributors
ref(docs): error on warnings for all Makefile targets
docs(*): add Troubleshooting Deis docs
Merge pull request #2346 from ngpestelos/patch-1

docs(deisctl): reword comment
Merge pull request #2361 from bacongobbler/import-do-docs

docs(contrib): refer to digitalocean guide
Merge pull request #2360 from bacongobbler/baremetal-docs-import

docs(installing_deis): import baremetal docs
Merge pull request #2336 from mboersma/testing-docs

docs(testing): add better instructions for contributors
Merge pull request #2359 from carmstrong/docs-add_troubleshooting_deis

docs(*): add Troubleshooting Deis docs
chore(release): update version to v0.15.1
Merge pull request #2366 from mboersma/release-0.15.1

chore(release): update version to v0.15.1
chore(release): update version in master to v0.15.1+git
Merge pull request #2367 from mboersma/release-0.15.1+git

chore(release): update version in master to v0.15.1+git
Merge pull request #2352 from johanneswuerbach/patch-6

fix(tests): Allow TLS
fix(build.sh): fail on errors in Dockerfile two-tier builds

Without "set -e" at the top of each build.sh script, errors would
not propagate to the parent "docker build" process. In the case
of controller, this was masking a missing dependency which is now
fixed.
fix(registry): prefix "apt-get install" with "apt-get update"