Merge branch 'add_walleth' into 'master'

Add WALLETH (0.15)

See merge request !2329

metadata/org.walleth.txt

@@ -0,0 +1,25 @@
+Categories:Money
+License:GPL-3.0
+Web Site:http://walleth.org
+Source Code:https://github.com/walleth/walleth
+Issue Tracker:https://github.com/walleth/walleth/issues
+
+Auto Name:WALLETH Ethereum Wallet
+Summary:Ethereum wallet
+Description:
+Ethereum wallet. Currently on Rinkeby Testnet. With light-client option.
+.
+
+Repo Type:git
+Repo:https://github.com/walleth/walleth
+
+Build:0.15,15
+    commit=0.15
+    subdir=app
+    gradle=noFirebaseForFDroid
+    prebuild=sed -i -e '/google-services/d'  -e '/withFirebaseCompile/d' build.gradle
+
+Auto Update Mode:Version %v
+Update Check Mode:Tags
+Current Version:0.15
+Current Version Code:15