GC-11: Added a help subcommand to the tool:

- Updated functional test for checking on the help subcommand as well.
- Implemented the 'help' subcommand.
- Updated required function signature for the subcommand_parser
decorator (functions should return ArgumentParser instance).
- Fixed a typo in inline documentation.
- Updated the test for subcommand_parser decorator to be a more robust
when checking if function registration works.

GC-11: Implemented decorator mechanism for registering subcommands:

- Added decorator that will register the provided functions.
- Added a simple interface function for fetching list of such
registered functions.

GC-11: Updated CLI to display simple usage help:

- Added terse description to the CLI.
- Implemented small mechanism for invoking callback functions attached
to parser.
- Fixed some linting issues in setup script.

GC-11: Added intial dummy CLI skeleton implementation:

- Register entry point in the package setup script.
- Implemented a very basic main function as entry point that
constructs an empty argument parser.
- Implemented functional test for testing if the CLI tool gets invoked
correctly after installation.
- Added unit tests for implemented functionality.

GC-2: Added basic development documentation:

- Documented development environment set-up.
- Documented how to run the tests.
- Documented how to build documentation.

GC-2: Added tox configuration:

- Configured multiple environments for running tests against Python
3.4, 3.5, and 3.6.
- Configured environment for running linting tests.
- Configured environment for running documentation builds.
- Updated requirements for running linting tests.
- Updated pytest configuration to include running linting tests.
- Updated gitignore to exclude tox artefacts.

GC-2: Added flake8 configuration file:

- Updated package manifest file to include the flake8 configuration
file in generated source distribution.
- Set the maximum line length limit to 160 characters.

GC-2: Added coverage configuration and updated manifest file:

- Include only the actual module files in the coverage reporting.
- Addd comments to gitignore file.
- Updated gitignore file to exclude test artefacts.
- Updated manifest file to include documentation files, as well as
test configuration file.
- Added pytest configuration file that ensures coverage plugin is
enabled and that report is stored in html format in the coverage
directory.

GC-2: Added initial package setup configuration:

- Updated gitignore to exlude some of the build and Python artefacts.
- Added manifest file, including a number of files that are not
normally being distributed.
- Created setup.cfg that overrides default command for running tests.
- Added initial setup.py.

GC-2: Adding initial documentation skeleton with some basic information about the project:

- Added basic documentation describing the project.
- Updated gitignore file to ensure documentation build artifacts stay
out of the repository.
- README file placed at top directory for convenient access.