Update the ubuntu build setup from 17.04 to 17.10

An updated image has been pushed to the docker hub, so update with

./scripts/update-docker.sh

README.md

@@ -18,7 +18,7 @@ This source folder is mounted as the `/root/termux-packages` data volume, so cha
 in sync between the host and the container when trying things out before committing, and built
 deb files will be available on the host in the `debs/` directory just as when building on the host.
 
-The docker container used for building packages is a Ubuntu 17.04 installation with necessary packages
+The docker container used for building packages is a Ubuntu 17.10 installation with necessary packages
 pre-installed. The default user is a non-root user to avoid problems with package builds modifying the system
 by mistake, but `sudo` can be used to install additional Ubuntu packages to be used during development.
 
@@ -34,7 +34,7 @@ Note that building packages can take up a lot of space (especially if `build-all
 
 Build environment without Docker
 ================================
-If you can't run Docker you can use a Ubuntu 17.04 installation (either by installing a virtual maching guest or on direct hardware) by using the below scripts:
+If you can't run Docker you can use a Ubuntu 17.10 installation (either by installing a virtual maching guest or on direct hardware) by using the below scripts:
 
 - Run `scripts/setup-ubuntu.sh` to install required packages and setup the `/data/` folder.
 

scripts/Dockerfile

@@ -4,7 +4,7 @@
 # 	docker push termux/package-builder
 # This is done after changing this file or any of the
 # scripts/setup-{ubuntu,android-sdk}.sh setup scripts.
-FROM ubuntu:17.04
+FROM ubuntu:17.10
 
 # Fix locale to avoid warnings:
 ENV LANG C.UTF-8