Adds Unit Tests

Adds a composer.json to include phpunit as a developer dependency. Adds
a .gitignore file to ignore vendor and bin directory resulting from a
composer install.

Adds a phpunit.xml.dist file with basic test suites setup. Adds a test
bootstrap file to bring in the required classes for our tests.

Adds unit tests for all currently public methods in Gitphull.php to
ensure functionality is working correctly.

Fixes a bug where new branches cloned from Gitphull are not cloned into
the proper branch.

Edits setLocation to add a trailing slash if one is not included.
Escapes Shell Arguments in Unit Tests

Uses escapeshellarg around all variables used in shell commands in
the unit tests to prevent against horrible things happening if they
are maliciously changed.
Merge pull request #1 from janiv/phpunitTests

Adds Unit Tests