Fixed order of notebook loading and kernel starting....
Fixed order of notebook loading and kernel starting.
For security reasons, the kernel should not be started until
after the notebook content is completely loaded and on the page.
This prevents people from creating notebooks that run nasty code
on the users machine at load time.
In order to implement this, we had to create a CodeCell.set_kernel
method that allows the kernel attribute of a CodeCell to be set
at a later time. This also fixes some error messages we were
seeing related to the kernel's channels not being setup properly
when a send was attempted.
