./make: script to create android builds (#315)

This PR introduces the `./make` script. For now, this script knows how to make Android releases. We have code in https://github.com/ooni/probe-cli/pull/311 that builds other artifacts in this repository.

Because our current concern is https://github.com/ooni/probe/issues/1444, in this PR, I have chosen to keep the Android code necessary to fix https://github.com/ooni/probe/issues/1444.

Additionally, this PR removes the script to publish to Bintray. This change part of the https://github.com/ooni/probe/issues/1440 cleanup effort.

MOBILE/android/go

@@ -0,0 +1,16 @@
+#!/bin/sh
+
+# print the fullpath of the go we're using so that it's part
+# of the build logs and we can easily increase our confidence
+# that we are using the right go binary.
+
+echo -n "$0: checking for go... "
+go=`command -v go`
+if [ -z $go ]; then
+    echo "not found"
+    exit 1
+fi
+echo "$go"
+
+set -x
+$go "$@"