merge two git repositories to one (jzboot xburst-tools --> xburst-tools)

[Xiangfu Liu]

Hi Peter

I found the git submodule is not easy to use. needs more commands
to keep jzboot update then I search a little about merge two git
repositories to one. found this:
  http://stackoverflow.com/questions/1425892/how-do-you-merge-two-git-repositories

I have follow the the first answer 'Subtree merge' do that in local.
if you think this is ok. I will do a git push under xburst-tools.git
then mark jzboot as read only and update the jzboot page.

xiangfu