Updates copyright
Updates to short array syntax
Adds credentials class and interface
Updates phpunit version
Moves tests out of their own namespace
Removes ParameterCollection
Renames classes to better convey functionality
Updates Credentials class and interface
Adds new dev dependencies
New exception
New exception
New request adapters (will be broken out later)
Updates to the renamed classes
New RequestInterface
Updates existing classes and tests
Removes, ignores composer.lock
Adds PHP 5.6 to .travis.yml
Changes validateSignature to isValid
Shuffles lib organization, adds interfaces
Adds guzzlehttp as dev requirement