[CONTRIBUTING] Remove reference to HISTORY.textile

This was a remnant from the Project Hydra "Making Changes" document.
Thanks to Eli Young for pointing this out.
[action/deploy/environment] (GH-260) Handle \W in environment names

Version 1.4.0 broke handling of environment names containing \W. When
determining which branch to check out, it compares the unnormalized
environment name(s) passed in on the command line to the normalized
environment name returned by the backend. This normalizes the names
passed in on the command line before the comparison happens.
Merge pull request #261 from elyscape/issue/1.4.x/gh-260-deploy-nonstandard-environment-names

[action/deploy/environment] (GH-260) Handle \W in environment names
[action/deploy/environment] (GH-260) Handle \W in environment names

Version 1.4.0 broke handling of environment names containing \W. When
determining which branch to check out, it compares the unnormalized
environment name(s) passed in on the command line to the normalized
environment name returned by the backend. This normalizes the names
passed in on the command line before the comparison happens.
Merge branch 'backport/1.4.x/gh-260-normalize-cmdline-branch-names' into 1.4.x
Merge branch '1.4.x'
[spec_helper] Acknowledge Faraday::Builder warning
[util/subprocess] Remove unused IO class, reorder runners
[subprocess/posix/runner] Clean up pipe generation
[subprocess/posix/runner] Handle ENOENT and EACCES exec failures
[subprocess/posix/runner] Add spec coverage
[subprocess/runner] Remove #start and #wait

The start and wait methods have strange semantics when the given command
fails to execute, and are not used. They can be removed.
[spec] extract subprocess runner shared examples
[subprocess] Reorganize namespace