fix(pip): update location of pip installer

raw.github.com URLs have moved to raw.githubusercontent.com, and
wget was seeing a 301 (Moved Permanently) under the covers. curl
does not automatically follow such a redirect, so the URL change
caused an error for deis/tester, but was benign here.
fix(builder): do not check for a Procfile

Some applications do not have a Procfile present before a buildpack
compile step[1]. If a Dockerfile is not present, then the builder
should make the assumption that this app is a buildpack app.

[1]: https://github.com/bacongobbler/heroku-buildpack-jekyll/blob/master/bin/release
tests(travis-ci): remove branch restrictions for test runs

We previously restricted travis-ci.org builds to just the `master`
and `release` branches, but that isn't necessary. To help with
developing new integration tests, have Travis build any Deis branch.
docs(contributing): split out DCO
refactor(contrib/rackspace): create private network on Rackspace

Previously, we were creating servers using the default Rackspace
ServiceNet as the private network. This means that they are feasibly
accessible by other servers on that network. This commit ensures
we are creating a new, private network for deis and not connecting
to the ServiceNet any longer.

closes #891
fix(docker): use btrfs inside builder

We have seen mixed usage of aufs and btrfs cause problems before. On
CoreOS, btrfs rules the day, so use that.
fix(client): return non-zero on errors

Some commands were inconsistent and returned 0 when an error
occurred. This makes the client more consistent with errors.

closes #767
refactor(client): remove provider functions

Deis no longer handles provider code, so these functions should not
exist in the client.
feat(client): add auth command

It's handy to have a `deis help auth` command which will show off the
documentation for the auth commands available to the user.
feat(client): add --app option to apps:run

All of the other apps commands have a --app option. This commit
introduces that option to the apps:run command as well.

fixes #722
docs(README): install nfs on Ubuntu

Ubuntu does not have nfs support by default. You must install nfs-kernel-server
to get nfs support. Adding this to the documentation will make the process for
developing Deis on Ubuntu a little clearer.

closes #896
Switch master to v0.9.0.
Merge pull request #893 from deis/btrfs-builder

fix(docker): use btrfs inside builder
Merge pull request #900 from hyao/master

docs(README): install nfs on Ubuntu
Merge pull request #885 from deis/travis-integration

tests(travis-ci): remove branch restrictions for test runs
Merge pull request #880 from deis/pip-url-moved

fix(pip): update location of pip installer
Merge pull request #892 from deis/rs_private_network

refactor(contrib/rackspace): create private network on Rackspace
Merge pull request #887 from deis/split-dco

docs(contributing): split out DCO
Merge pull request #899 from deis/722-app-run

feat(client): add --app option to apps:run
chore(controller): remove unused gevent package