Merge pull request #375 from justinsb/avoid_nil_pointer_if_no_openstack_image

builder/openstack: If no image is generated, just return nil
Update CHANGELOG
Merge pull request #376 from justinsb/try_parse_pkcs8

communicator/ssh: If PKCS1 parsing of the SSH key fails, try PKCS8
Update CHANGELOG
website: page titles on provisioner docs
website: fix typo s/script/shell/ provisioner
builder/openstack: don't hardcode "DFW" and make region required
website: document required openstack region setting
website: fixup some underscores to not be emphasis in the AWS docs
website: add openstack to the intro platforms list
builder/openstack: region is now required
Merge branch 'upstream'

Conflicts:
	builder/openstack/access_config.go
	builder/openstack/builder.go