Close #709: Improve user creation (#725)

* Allow to specify a custom username in "pmbootstrap init"
* Build chroots have "pmos" instead of "user" as username now
* Installation user UID is 1000 now (as in all other Linux distributions)
* Adjust autologins
* postmarketos-base: enable wheel group for sudo, removed previous sudoers file
* Implement safe upgrade path:
We save the version of the work folder format now, in $WORK/version.
When this file does not exist, it defaults to 0.
In case it does not match the currently required version
(pmb.config.work_version), then ask the user if it should
automatically be upgraded.

pmb/install/recovery.py

@@ -66,8 +66,8 @@ def create_zip(args, suffix):
         # Move config file from /tmp/ to zip root
         ["mv", "/tmp/install_options", "install_options"],
         # Create tar archive of the rootfs
-        ["tar", "-pczf", "rootfs.tar.gz", "--exclude", "./home/user/*",
-         "-C", rootfs, "."],
+        ["tar", "-pczf", "rootfs.tar.gz", "--exclude",
+         "./home/" + args.user + "/*", "-C", rootfs, "."],
         ["build-recovery-zip"]]
     for command in commands:
         pmb.chroot.root(args, command, suffix, working_dir=zip_root)