add apk release script

contrib/make_apk

@@ -1,2 +1,17 @@
 #!/bin/bash
-pushd ./gui/kivy/; make apk; popd
+
+pushd ./gui/kivy/
+
+if [[ -n "$1"  && "$1" == "release" ]] ; then
+    echo -n Keystore Password:
+    read -s password
+    export P4A_RELEASE_KEYSTORE=~/.keystore
+    export P4A_RELEASE_KEYSTORE_PASSWD=$password
+    export P4A_RELEASE_KEYALIAS_PASSWD=$password
+    export P4A_RELEASE_KEYALIAS=electrum
+    make release
+else
+    make apk
+fi
+
+popd