Use a proper domain name regex

This allows all possible domain names based on RFC 1035.

[delivers #69232044]
Checks that the file size is within limits before adding to the blobstore
Merge remote-tracking branch 'origin/pr/211'

Signed-off-by: Kai Zhang <kaizhang@cn.ibm.com>

Conflicts:
	app/models/runtime/domain.rb
Merge remote-tracking branch 'origin/pr/214'

Signed-off-by: Kai Zhang <kaizhang@cn.ibm.com>