call copy_attachment() after configure() and move attachment files

call copy_attachment() after configure() and move attachment files

- Call BaseImager.copy_attachment() after BaseImager.configure()
  Post scripts on configure() cannot access attachment files which come from install_root.
  So call copy_attachment() after running post scripts.

- Move attachment files not copy.
  If copying attachment files from install_root, then attachment files remain in install_root.
  So use mv instead of cp for deduplication.

Change-Id: Ie7a1d516331e29eaba975bc186b9644b96c17fbc
Signed-off-by: Dohyung Kim <dohyung2.kim@samsung.com>