sstate-diff-machines.sh: Return non-zero return code when there was some failure detected

* add --analyze option, which is useful when using from jenkins job
  where you don't want to read output just to dectect how bad it was
* I was always using something like this inside jenkins job, but better
  to share it in original script

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
test-dependencies.sh: Return non-zero return code when there was some failure detected

* this is useful when using from jenkins job where you don't want to read
  output just to dectect how bad it was
* add .log suffix to all files, so they can be easily downloaded from
  http servers without default mimetype set to something useful
* add recipes failed in step 1 to steps 2 and 3 to generate standalone
  logs for them

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>