Moves CoverageChecker into Build\Util Namespace

Context is everything. The namespace helps communicates the context in
which the class is designed to be used. The build process, like in
travis-ci, happens in a terminal/console, and outputs text. By merely
moving this class into this namespace, it becomes appropriate for the class
to output text colorized for the terminal. Seems to make sense (for now).
Eliminates Build Function Files

Eliminates function files by moving the function definition into the
publish coverage reports script.
Moves Functions into Class in Publish Coverage Reports

Moves the functions into a class. One step closer to a complete
refactoring.
Hides S3 Instance in Publish Coverage Report

Hides the method to get the S3 object inside the class. Removes from
parameter and argument list.
Removes Method to Get S3 Object

Eliminates the getS3 method by moving it's logic into the function where it
is called.
Converts Bucket Class to Object in Publish Coverage Report

Adds constructor method to Bucket class, collects values in one place then
constructs bucket.
Adds Alternate Way to Get S3 Bucket Credentials

Uses a closure in the script to collect arguments for the Bucket
constructor. This way the script can be run even when it's not on travis,
which will be helpful for the next refactoring steps.
Renames Env Variables for Publish Coverage Reports

Renames all the env vars in travis configs and updates script to match.
Moves Bucket Class to Class File

Moves the Bucket class out of the build script and into it's own class
file. Modified to instantiate S3 object in constructor and not store key
and secret. Removes old comments from use statements.
Moves AWS SDK Into Main Composer Requires

Since a class is using the AWS SDK, and that class isn't restricted to a
dev environment, the AWS SDK must need to be moved into the main requires
in the composer file.