Tweak info log level in build steps to #info

This will show which commands are executing, their environment, and retries.
This commit restores the original parity with previous output, without
including all the -l debug information.
Refactor sugars into a module instead of a magical load-time thing

This commit moves the sugars into a "Sugarable" mixin that defines a `node`
object and wires all the pieces together for a DSL to include Chef Sugar.
Individual classes can then `include Sugarable` and they get the DSL.

This commit eliminates the nasty load-time stuff that I did originally.
Refactor "omnibus release" into a non-S3-specific thing

The current release command is heavily tied to S3. This commit extracts
the package-specific bits into a new `Package` class, which removes
much of the logic from the S3 releaser. These methods are now
available in future releasers.

This commit renames the CLI command from "omnibus release" to
"omnibus publish". As a team, we agreed that "release" was an incorrect
verb for the action taking place. NOTE: this commit does not include a
deprecation yet. That will be done in a future commit.
Fix @todo comment in Software
Freeze the DEFAULT_CONFIG constant
Remove duplicate test in publisher_spec