previewbuildscript: Update bitbake and meta-oe revisions

This needs to be applied together with 2 changes to meta-webos:
https://g2g.palm.com/1677
https://g2g.palm.com/1678

But because those 2 changes depend on newer meta-oe they will fail in review verification

meta-webos revision should be updated atomically with meta-oe upgrade, so rebase this when they are applied and squash meta-webos upgrade (with right revisions) to last commit here.