Added support for PSR-3

[dragonmantank]

Description

This adds support for PSR-3, which enables standardized logging. It also allows enabling a "debug" flag that will log out a Request and associated Response if a logger is set at DEBUG level.

This does not provide a logger itself, just allows a PSR-3 compatible logger to be passed in via the MapFactory and setting something to the PSR\Log\LoggerInterface key. The user is responsible for providing the logger that the client will use.

This also allows us to add logging capabilities to the individual APIs as well later down the line.

Motivation and Context

Logging is a standard thing most applications do. Users can now get basic logging from our system. Request/Response logging is available as it is the most common debugging information that is needed.

How Has This Been Tested?

Test scripts using Monolog as a logging solution.

Example Output or Screenshots (if appropriate):

To enable logging, you will need to enable the new debug flag as well as pass a PSR-3 compliant logger such as Monolog (not shipped with our library):

$client = new Vonage\Client(new Basic('abcd1234', 's3cr3tk3y'), ['debug' => true]);
$logger = new Monolog\Logger('test');
$logger->pushHandler(new StreamHandler(__DIR__ . '/log.txt'));
$client->getFactory()->set(LoggerInterface::class, $logger);

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[codecov-io]

Codecov Report

Merging #272 (f283426) into master (c9bd018) will decrease coverage by 0.11%.
The diff coverage is 48.57%.

@@             Coverage Diff              @@
##             master     #272      +/-   ##
============================================
- Coverage     80.56%   80.45%   -0.12%     
- Complexity     2446     2460      +14     
============================================
  Files           166      167       +1     
  Lines          6042     6077      +35     
============================================
+ Hits           4868     4889      +21     
- Misses         1174     1188      +14     

Impacted Files	Coverage Δ	Complexity Δ
src/Client.php	76.67% <26.08%> (-4.19%)	82.00 <4.00> (+6.00)	⬇️
src/Client/Factory/MapFactory.php	86.48% <75.00%> (+4.66%)	16.00 <0.00> (+3.00)
src/Logger/LoggerTrait.php	100.00% <100.00%> (ø)	5.00 <5.00> (?)

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[GregHolmes]

I've added one suggestion for the README, as you hadn't included the full namespace for the Basic class.