shell: Unify import pattern

We do not spell out kas. elsewhere, only here so far. Unify that.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>

kas/shell.py

@@ -26,9 +26,9 @@
 
 import subprocess
 import os
-from kas.libkas import kasplugin
-from kas.context import Context
-from kas.libcmds import (Macro, Command, SetupDir, SetupEnviron,
+from .libkas import kasplugin
+from .context import Context
+from .libcmds import (Macro, Command, SetupDir, SetupEnviron,
                       WriteBBConfig, SetupHome, ReposApplyPatches,
                       CleanupSSHAgent, SetupSSHAgent, SetupRepos)