Add compatibility to Android API 26+ with channel ID

[jsamr]

This PR fixes #1 and #2.

The set of changes can be summed up as follow

Upgrade appcompat (resolves #1)

• build.gradle Upgrade com.android.support:appcompat-v7 to 26.0.0 in order to avoid the deprecated Notification.Builder
• build.gradle Upgrade SDK to 26
• build.gradle Add google to build repositories to benefit from gradle 3
• build.gradle Add google to repositories to benefit from com.android.support:appcompat-v7:26.0.0
• android/src/main/java/com/staltz/reactnativeandroidlocalnotification/Notification.java replace android.support.v7.app.NotificationCompat with android.support.v4.app.NotificationCompat. That change resolves #1 because react native projects use the latests app compat library, in which android.support.v7.app.NotificationCompat does not exists.

Use channels for API 26+ (resolves #2)

• android/src/main/java/com/staltz/reactnativeandroidlocalnotification/Notification.java build method now has an API check and use the new Builder constructor
• android/src/main/java/com/staltz/reactnativeandroidlocalnotification/NotificationAttributes.java added channelID and channelName attributes
• README Document new attributes, channelID and channelName

Misc:

• build.gradle Replace deprecated compile with implements
• build.gradle buildTools version set to 27.0.3
• android/gradle/wrapper/gradle-wrapper.properties upgrade gradle distribution to 4.6 to use with latest android studio
• .gitignore add .vscode/

[elisechant]

@staltz @jsamr can we please resolve conflicts and merge? I am also having issues with channel.

[staltz]

Sorry, I don't intend to maintain this repository as an aggregator of contributions, it takes too much work from me, alongside hundreds of other repos I have. This repository itself was a fork of https://github.com/anysome/react-native-pure-notification , I recommend maintaining your own fork if these changes are important to you.