remove nbformat

ipython[nbformat] depends on jupyter_nbformat

IPython/testing/iptest.py

@@ -147,7 +147,7 b" have['zmq'] = test_for('zmq.pyzmq_version_info', min_zmq, callback=lambda x: x()"
 
 test_group_names = ['parallel', 'kernel', 'kernel.inprocess', 'config', 'core',
                     'extensions', 'lib', 'terminal', 'testing', 'utils',
-                    'nbformat', 'qt', 'html', 'nbconvert'
+                    'qt', 'html', 'nbconvert'
                    ]
 
 class TestSection(object):
@@ -282,8 +282,6 b" if not have['tornado']:"
     sec.exclude('nbconvert.post_processors.serve')
     sec.exclude('nbconvert.post_processors.tests.test_serve')
 
-# nbformat:
-test_sections['nbformat'].requires('jsonschema')
 
 #-----------------------------------------------------------------------------
 # Functions and classes

setup.py

@@ -271,7 +271,7 b' extras_require = dict('
     doc = ['Sphinx>=1.1', 'numpydoc'],
     test = ['nose>=0.10.1', 'requests'],
     terminal = [],
-    nbformat = ['jsonschema>=2.0'],
+    nbformat = ['jupyter_nbformat'],
     notebook = ['tornado>=4.0', pyzmq, 'jinja2', 'pygments', 'mistune>=0.5'],
     nbconvert = ['pygments', 'jinja2', 'mistune>=0.3.1']
 )