removed up `AbstractPlugin` getter functions.
added `final` to the members of `Platform`.
removed unused `Key` and `TypeLiteral` instances.
Merge branch 'feature/minor-cleanup' into develop

* feature/minor-cleanup:
  removed unused `Key` and `TypeLiteral` instances.
  added `final` to the members of `Platform`.
  removed up `AbstractPlugin` getter functions.
added a `FilterSpec` class to hold the filter and it's priority.
added `bindFilter` method to `AbstractPlugin`.
added `FilterSpec` to the `InjectorWrapper`.
modified `Platform` to add filters during the `run` phase.
added name to `FilterSpec` and switched to a builder pattern.
modified `getFilterSpecs` to return in priority order.
added a filter binder that can take a class as well as an instance.
cleaned up the filter classes.
added tests for `FilterBinder` and `FilterProvider`.
added javadocs to the filter classes.
Merge branch 'feature/filters' into develop

* feature/filters:
  added javadocs to the filter classes.
  added tests for `FilterBinder` and `FilterProvider`.
  cleaned up the filter classes.
  added a filter binder that can take a class as well as an instance.
  modified `getFilterSpecs` to return in priority order.
  added name to `FilterSpec` and switched to a builder pattern.
  modified `Platform` to add filters during the `run` phase.
  added `FilterSpec` to the `InjectorWrapper`.
  added `bindFilter` method to `AbstractPlugin`.
  added a `FilterSpec` class to hold the filter and it's priority.
added `findbugs` to the project and fixed bugs in `TypeLiterals`.