Remove legacy azure nbmanager
handle image size metadata in nbconvert html
remove base_kernel_url
Remove remaining refs to the Azure NB Manager
Add documentation for removal
Add pointers to simple nb manager and bookstore.
Change wording to say that the azure nb was actually removed
don't use combine option on ucs package

Caused problems with unicode.

It seems f9c32fcee337b6560ec31e25fba04cae6021b74a was actually the right fix for the original error, not faf51b858a8c5757944822ee1d75c11367e994f.

closes #5129
Some template static_url tweaks

- don't try to include version in static_urls that don't point to files
- use full static_urls (with extension) for backbone and underscore, so version can be computed

closes #5141
fix a link that was broken
Merge pull request #5150 from ivanov/fix-fonnesbeck-link

fix a link that was broken
fix IPython typo, closes #5155
Merge pull request #5156 from ivanov/fix-5155

fix IPython typo, closes #5155
remove append_json reference

we never had such a method
Merge pull request #5095 from minrk/image-size

handle image size metadata in nbconvert html
Merge pull request #5159 from ivanov/oops-json

remove append_json reference
Simplify implementation of TemporaryWorkingDirectory.

Closes gh-5160
Merge pull request #5089 from rgbkrk/azure_out

Remove legacy azure nbmanager
Merge pull request #5133 from minrk/latex-unicode-nightmare

Don't use combine option on ucs package

**never** use combine when mixing ascii and non-ascii chars or all the non-ascii chars will be rendered after the ascii one have been.
remove mktemp usage

mktemp is insecure, by the time the generated filename is used someone
else might have modified it.