Add Composer dependencies and PHPUnit config.
Update the readme text.
Add base test case class.
Add Travis badge to readme.
Add Travis configuration.
Add existing implementation and test cases.
Add exception classes.
Simplify Guzzle Client mock.

Removed expected call so that the required calls can be defined in the
using test cases.
Implement base `word` method call.

Implement the call for the basic `/word.json/{word}` request method.
Includes the associated test case.