mods to install mathjax from an explicitly downloaded tar or zip file
Refactor kernel managers in preparation for the EmbeddedKernel.
Implement EmbeddedKernel.
Add abstract base class (ABC) for sockets used in kernel.
BUG: QtKernelManagerMixin does not define PyQt4-safe signals.
DOC: Add an example showing off the embedded Qt console.
REFACTOR: Terminology change: 'embedded' -> 'in-process'.
DOC: Add module-level docstring to in-process kernel example.
DOC: Add information about in-process kernels to What's New.
BUG: GUI integration broken in the in-process kernel.
TST: Add some unit tests for in-process kernel and kernel manager.
TST: Add more unit tests for in-process kernel manager.
BUG: raw_input logic incorrect for in-process terminal frontend.
Ensure that in-process test group doesn't create global IPython singleton.

Since the in-process group makes its own shells, it should avoid
creating the global singleton.
TST: Skip pylab test for in-process kernel when matplotlib is missing.
a few fixes

- default back tom Mathjax2.0
- install to profile by default
- fix in doc
- fix bad return
create a ipynbv3 json schema and a validator

cf http://json-schema.org/
http://tools.ietf.org/html/draft-zyp-json-schema-03

autogenerated from
http://www.jsonschema.net/index.html#
then tweeked.

This version makes all our notedooks in docs/example/notebooks valid
change prompt_numper type

prompt number type was number or string ('*', '&nbsp')
require it to be either number, or null
prompt_number : number -> integer
number -> integer