Fix screwed up progress bars in Travis output (#1213)

Right now, they appear on screen when using --details-to-stdout. This
does not work well with Travis CI and screws up the log.

Disabling the progress bars in abuild works just like Alpine does it in
their Travis CI script: Exporting SUDO_APK as
"abuild-apk --no-progress" instead of "abuild-apk".

test_check_checksums.py: Run "pmbootstrap build_init" before building
any packages, so it is a bit less verbose (downloading the APKINDEX
files etc.). Later we run the build init code again (because we use
--strict while building the packages), but then the APKINDEX files
are already present. So overall the log is a bit shorter before the
building starts. (It is still logged to the logfile, which gets
printed on error anyway.)

pmb/chroot/init.py

@@ -135,7 +135,7 @@ def init(args, suffix="native"):
                                     chroot + "/usr/bin/qemu-" + arch_debian + "-static"])
 
     # Install alpine-base (no clean exit for non-native chroot!)
-    pmb.chroot.apk_static.run(args, ["--root", chroot,
+    pmb.chroot.apk_static.run(args, ["--no-progress", "--root", chroot,
                                      "--cache-dir", apk_cache, "--initdb", "--arch", arch,
                                      "add", "alpine-base"])