Implements full path for hash checks of binaries

Previously the hash check would work only against the filename,
and not using the relative path.

This change uses the whole relative path to allow indentical
filenames in different folder locations within the same repo.

Also updated the generate-sha256.py script to introduce the same
changes.

JIRA: RELENG-303

Change-Id: I3a59e015b708eb5a966690b9839e5e15ac5b64c7
Signed-off-by: lhinds <lhinds@redhat.com>