Setting notification icon on android

Support setting push notification icon on android. #45

Additionally:

• Bugfix: allow setting optimove credentials without optimobile credentials #42

Remove remaining manifest modifications

Remove conflicting manifest modifications (#41)

* remove manifest modifications

* update version

API consistency updates

1. Remove irrelevant manifest modifications (which may result in manifest merger conflicts)
2. minor tweaks to types in the ExampleApp
3. add signOutUser and pushUnregister API. Add to the ExampleApp
4. update android base sdk 6.* --> 7.0.1, use new api for requesting push token (pushRegister --> pushRequestDeviceToken)
5. when presenting in-apps return OptimoveInAppPresentationResult similar to other sdks

Add readme to the NPM package

Merge pull request #39 from optimove-tech/bump-sdk-version

Bump version to publish package readme

Cordova SDK initial release

Initial public release 🎉