Change $.post to this.post in the kernel js file

This makes it easy to override the post function for custom communication requirements.  Any replacement function, of course, needs to have the same semantics as $.post.
Adds markdown formatting to output cells
Update notebook.rst

Updating broken reference to notebook examples 

Since the notebook directory doesn't contain a readme anymore, updating to point to the index notebook rendered via nbviewer
Update parallel_intro.rst

fixing broken link to examples directory and updating the github link to point to the nbviewer index page
Merge pull request #5693 from mohanraj-r/patch-2

Update parallel_intro.rst to fix a broken link to examples
Merge pull request #5692 from mohanraj-r/patch-1

Update notebook.rst fixing broken reference to notebook examples readme
Merge pull request #5602 from jasongrout/kernel-js-post

Change $.post to this.post in the kernel js file
Fix non-ascii spaces in comment.

Closes gh-5697
Merge pull request #5648 from andrewjesaitis/ticket4756

Adds markdown formatting to output cells
Merge pull request #5644 from jhamrick/master

Do not record memory addresses of display objects