fix(tests): Allow TLS

Fixes https://github.com/deis/deis/issues/2230
docs(*): add Troubleshooting Deis docs
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
docs(managing_deis): add MDS removal instructions
docs(*): specify required CoreOS version
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"
Merge pull request #2368 from carmstrong/docs-add_remove_mds

docs(managing_deis): add MDS removal instructions
Merge pull request #2369 from carmstrong/add_coreos_version

docs(*): specify required CoreOS version
Merge pull request #2362 from mboersma/catch-build-sh-errors

fix(build.sh): fail on errors in Dockerfile two-tier builds
style(logger): add code doc strings
style(deisctl): add code doc strings and fix minor issues