These changes have been made, so that this project can be potentially
used within a Docker container. These dependencies will have to exist
one way or another for Git Review, as most of the Git Review console
commands utilise 3rd party Composer packages such as PhpCSFixer and
PHPCodeSniffer.

The `composer.json` file has been updated to try to allow flexibility
for end users, who wish to use different versions for these 3rd party
packegs.

For example Project could use `v1.6` for PHPCSFixer as a require
dependency in their `composer.lock`, and Project B could have `v2.12` as
their dependency requirement. It would introduce breaking changes as the
user would have to reconsider their dependencies, without adding this
flexibility.