Add Android-specific options

Now the app can:
-Set the channel name and description
-Set the notification subtext
-Add a "Close" action to the notification, along with customizing the action text and icon

Fixed bugs:
-Icon is never used if it's in "drawable" rather than "mipmap"
-Used "Compat" library to make backwards compatibility easier

README.md

@@ -145,11 +145,17 @@ The title, text and icon for that notification can be customized as below. Also,
 cordova.plugins.backgroundMode.setDefaults({
     title: String,
     text: String,
-    icon: 'icon' // this will look for icon.png in platforms/android/res/drawable|mipmap
-    color: String // hex format like 'F14F4D'
+    subText: String, // see https://developer.android.com/reference/android/support/v4/app/NotificationCompat.Builder.html#setSubText(java.lang.CharSequence)
+    icon: 'icon', // this will look for icon.png in platforms/android/res/drawable|mipmap
+    color: String, // hex format like 'F14F4D'
     resume: Boolean,
     hidden: Boolean,
-    bigText: Boolean
+    bigText: Boolean,
+    channelName: String, // Shown when the user views the app's notification settings
+    channelDescription: String, // Shown when the user views the channel's settings
+    allowClose: Boolean, // add a "Close" action to the notification
+    closeIcon: 'power', // An icon shown for the close action
+    closeTitle: 'Close' // The text for the close action
 })
 ```
 
@@ -205,4 +211,4 @@ Made with :yum: from Leipzig
 [changelog]: CHANGELOG.md
 [apache2_license]: http://opensource.org/licenses/Apache-2.0
 [appplant]: http://appplant.de
-[meshfields]: http://meshfields.de
+[meshfields]: http://meshfields.de