Expand images on tap (#315)

* Detect click on images in WebView

* First stub of the fragment to show the image in full screen

* Scale image dimension to fit the display

* Hide toolbar from Image view

* Add back button to the Image view

* Open one image on tap

* Allow zooming on images

* Revert to using Toolbar for navigation.

* Remove vibration when opening the Image view

* Do not open links associated with images

* Send all images in the webpage to the Image fragment.

* Change image on swipe

* Store article images in cache in background.

* Use PhotoView in place of WebView to display images. Implemented a pager to swipe through images.

* Removed debugging logging.

app/build.gradle

@@ -138,6 +138,9 @@ dependencies {
     // Pager
     implementation 'me.relex:circleindicator:2.0.0@aar'
 
+    //PhotoView
+    implementation 'com.github.chrisbanes:PhotoView:2.0.0'
+
     implementation 'androidx.core:core-ktx:1.1.0-beta01'
 
     implementation "androidx.lifecycle:lifecycle-livedata:$lifecycle_version"