118 - Implement shared album feature (#124)

* New features 
  - Share album. Users can now create albums to share with existing people on the network.
  - Owner can delete the album.
  - Owner can invite the additional users to the album.
  - Shared users and the owner can add additional assets to the album.
* In the asset viewer, the user can swipe up to see detailed information and swip down to dismiss.
* Several UI enhancements.

mobile/android/app/build.gradle

@@ -81,4 +81,5 @@ flutter {
 
 dependencies {
     implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
+    implementation 'com.android.support:multidex:1.0.3'
 }