QA:Installer image presence test case

Description

This test case checks that the installer images are present, listed in the metadata, and not corrupt.

How to test

1. open .treeinfo
2. confirm that the arch listed in the [general] section is correct
3. confirm that the files listed in the [images-$ARCH] section are present and non-empty
4. confirm that a [stage2] section is present and lists a mainimage item
5. confirm that the stage2 image is present and non-empty
6. check that each of the listed files matches the checksum specified in the [checksums] section

Expected Results

1. .treeinfo exists
2. listed arch is correct
3. boot images for the given arch are present and correct
4. stage2 image is present and correct