buildman: Move to absolute imports

At present buildman sets the python path on startup so that it can access
the libraries it needs. If we convert to use absolute imports this is not
necessary.

Move buildman to use absolute imports. Also adjust moveconfig.py too since
it uses some buildman modules and cannot work without this.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/buildman/toolchain.py b/tools/buildman/toolchain.py
index 4456a80..a354049 100644
--- a/tools/buildman/toolchain.py
+++ b/tools/buildman/toolchain.py
@@ -10,7 +10,7 @@
 import tempfile
 import urllib.request, urllib.error, urllib.parse
 
-import bsettings
+from buildman import bsettings
 import command
 import terminal
 import tools