Remove separate 'GUI' banner for ipykernel

See ipython/ipykernel#101

This will break compatibility with ipykernel releases before that PR is
merged, so milestoning for 5.0.

Author: takluyver

IPython/core/usage.py

@@ -544,10 +544,6 @@
 object?   -> Details about 'object', use 'object??' for extra details.
 """
 
-gui_note = """\
-%guiref   -> A brief reference about the graphical user interface.
-"""
-
 default_banner_parts = [
     'Python %s\n' % (sys.version.split('\n')[0],),
     'Type "copyright", "credits" or "license" for more information.\n\n',
@@ -557,12 +553,8 @@
     quick_guide
 ]
 
-default_gui_banner_parts = default_banner_parts + [gui_note]
-
 default_banner = ''.join(default_banner_parts)
 
-default_gui_banner = ''.join(default_gui_banner_parts)
-
 # page GUI Reference, for use as a magic:
 
 def page_guiref(arg_s=None):