Fixes #1506.

Document available environment variables

travis: update go versions

As discussed at https://github.com/github/hub/pull/1573

Enforce unix eol in bash script files through .gitattributes

Contributor Covenant Code of Conduct

Document the availability of the development version.

Pass file descriptors to cmd.NewWithArray

Fix windows build

Add plan9port rc shell support

Add Fedora Linux installation instructions

Add ability to delete releases

Fixes https://github.com/github/hub/issues/1423

When any of these global flags are passed, don't try to decorate the
output as if `git help` was invoked.

Fixes https://github.com/github/hub/issues/1446

`git rev-parse --show-toplevel` returns an empty string with success
status when inside a bare git repo.

This avoids the go crash and also tweaks `hub issue` and `hub
pull-request` to work even if current working directory name couldn't be
obtained because it's only used for looking up issue/PR templates, which
isn't critical functionality.

Fixes https://github.com/github/hub/issues/1331

Remove trailing slashes from the $TMPDIR variable

Fix Code of Conduct hyperlink in CONTRIBUTING

Sort hub commands

reset-console