BREAKING CHANGE: Update API for connection, communication channel state and is browser value (#14)

* refactor(lib, example, example_full): use streams for communication channel and is ios browser

* feat: add abstract toJson() to message

* refactor: add deprecations for nearby_service

* feat(example): update main.dart

* feat(nearby_service): add comments

* feat(nearby_service_platform_interface): add deprecation to getConnectedDeviceStream

* feat(nearby_service/message): add concrete implementation for toJson()

* feat(nearby_service/android): add deprecations

* fix(nearby_service/android): reset check for android device

* fix(nearby_service/ios): change ios service to deprecations variant

* chore(nearby_service): edit deprecation messages

* chore: update gitignore

* doc: add CONTRIBUTING file

* doc: update CONTRIBUTING file

* chore: update CONTRIBUTING.md

* chore: update CONTRIBUTING.md

* chore: version 0.1.0

* fix(example_full): move startListeningCommunicationChannelState() upper

.gitignore

@@ -34,4 +34,5 @@ build/
 **/Podfile.lock
 
 # FVM Version Cache
-.fvm/
+.fvm/
+playground/*