docs(install-deisctl): remove extra installer links and simplify doc
ref(gitignore): clean up old ignores, remove os-specific files

files to be ignored like .DS_Store on OSX should exist in a global
.gitignore file, where it is ignored across all repositories.

See https://help.github.com/articles/ignoring-files/#create-a-global-gitignore
chore(*): bump CoreOS to 509.1.0 for Docker vulnerability

This PR updates CoreOS to include
[Docker 1.3.2](https://github.com/docker/docker/blob/master/CHANGELOG.md#132-2014-11-20)
which includes [important security fixes](https://groups.google.com/forum/#!msg/docker-user/IrjXTHA6jJc/ZToMGL2yG_AJ).

In addition to upgrading to Docker 1.3.2, we are addressing the
secure-by-default registry settings in #2578 (these changes were
introduced in Docker 1.3.1).

Note that DigitalOcean and Rackspace do not yet have CoreOS 509.1.0.
fix(contrib): add --insecure-registry flag for docker 1.3.2

Deis' registry is insecure. Docker is secure-by-default, which means
that we must now whitelist insecure registries on each and every daemon.
fix(contrib): add other RFC1918 private addresses
chore(builder): bump Docker to 1.3.2
fix(contrib/coreos): fix usage of --insecure-registry
docs(installing_deis): add private network address requirement
docs(contributing): clean up insecure-registry language
Merge pull request #2564 from mboersma/simpler-install-deisctl

docs(install-deisctl): remove extra installer links and simplify doc
fix(builder): explicitly call out $TMP_DIR on `docker cp`

https://github.com/docker/docker/commit/31d1d733037b22591e2dd2edfe6c4d2d4b8086cc
prevents a breakout in ApplyLayer, which also seems to break
`docker cp <container_id>:<src_path> .`. This change explicitly calls
out our working directory (TMP_DIR) which behaves the same as before.
Merge pull request #2579 from carmstrong/coreos_beta_channel

chore(*): bump CoreOS to 509.1.0 for Docker vulnerability
docs(managing_deis): add warning to CoreOS upgrade
Merge pull request #2583 from carmstrong/docs-upgrade_warning

docs(managing_deis): add warning to CoreOS upgrade
Merge pull request #2566 from bacongobbler/gitignore-cleanup

ref(gitignore): clean up old ignores, remove os-specific files