Bugfix for PluginManager loading with no registered Plugins

Fixed

• Fixes an error where PluginManager::getLoadedPlugins would throw an error after the plugin loading process should
  have taken place if there were no registered Plugins. Now, when calling getLoadedPlugins with no registered Plugins
  found an empty array will be returned.

Introduce Settings and various improvements

Please see CHANGELOG for more details.

Allow for NativeDriver signal handling

Add initial signal watcher to kill app (#106)

* Add initial signal watcher to kill app

In practice not responding to SIGINT caused end users to forcefully shut
down the underlying architecture running the application. This could
mean forcefully killing docker containers as oppoased to gracefully
handling exit requests. This submits an initial, untested,
implementation to watch for signals to quit the app.

* put a wrapper around pcntl extension for now

* better extension checking

* make sure var is defined

Bugfix for AbstractApplication exception handling

Throw exceptions from AbstractApplication (#105)

* Throw exceptions from AbstractApplication

Unhandled exceptions could potentially result in squashed exceptions
based on the logger that was used for the Application. This changes the
default behavior to always rethrow the exception after logging... Each
Application implementation should define what exceptions it can handle
and which ones it can't.

* Add tests

* fix code lint

Allow better state manipulation for AbstractApplication

Allow abstract application better control over state (#104)

* Allow abstract application better control over state

* fix code lint

Introduces Settings

An initial release of the new Settings functionality. The API for Settings is still subject to potential changes after this version has seen some amount of use.

Improved Exception logging

Please see CHANGELOG for more details.

Initial 3.0 release

Please see CHANGELOG for more details.

Refactors Application::execute -> start() and stop()

Please see CHANGELOG for more details.

Fixes DependencyGraph bugs

Please see CHANGELOG for more details.