Add comments for DeployImageDialog 'standalone' part of codes to make it
easy to read.
And tweak some strings.
(Bitbake rev: b0e604d3d6dbfcaeac0a2e0e4399aeb4327f8cbc)
Signed-off-by: Kang Kai <kai.kang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>