Merge tag '4.0.0-beta4' into develop

Release 4.0.0-beta4
Fix an example that uses a deleted component.
Merge pull request #27 from zhaojunz/patch-1

Fix an example that uses a deleted component.
Put API methods at top of file. Add helpers for multibinder extensions.
Update InjectorExtension to include Annotation scala magic.
Upgrade to guice-beta5
Rename Multibinder filenames to ScalaMultibinder to match actual class name.
Rewrite Multibindings to use an internal Guice Module.
Implement a Scala version of MapBinder.
Update the readme for option/map/multi binding changes.
Implement a Scala version of OptionalBinder.
Add a test for when the Optional does not contain a value
Fix a Scala warning about missing symbols

Scala needs all annotation symbols to be present at compile time.
Merge commit 'pull/origin/33' into develop
Merge commit 'pull/origin/30' into develop
Cleanup now redundant import
Merge commit 'pull/origin/32' into develop
Add more tests for Option/Map/Multibinder

* Add missing matchers to SetProviderSpec
Update ScalaTest
Add reserved word gotcha