Fix sympy profile to work with sympy 0.7.

Sympy 0.7 no longer supports x,y,z = symbols('xyz').
symbols ('xyz') is now a single symbol 'xyz'.

Change the sympy profile to symbols(x,y,z).

IPython/config/profile/sympy/ipython_config.py

@@ -1,30 +1,30 b''
 c = get_config()
 app = c.InteractiveShellApp
 
 # This can be used at any point in a config file to load a sub config
 # and merge it into the current one.
 load_subconfig('ipython_config.py', profile='default')
 
 lines = """
 from __future__ import division
 from sympy import *
-x, y, z = symbols('xyz')
-k, m, n = symbols('kmn', integer=True)
+x, y, z = symbols('x,y,z')
+k, m, n = symbols('k,m,n', integer=True)
 f, g, h = map(Function, 'fgh')
 """
 
 # You have to make sure that attributes that are containers already
 # exist before using them.  Simple assigning a new list will override
 # all previous values.
 
 if hasattr(app, 'exec_lines'):
     app.exec_lines.append(lines)
 else:
     app.exec_lines = [lines]
 
 # Load the sympy_printing extension to enable nice printing of sympy expr's.
 if hasattr(app, 'extensions'):
     app.extensions.append('sympyprinting')
 else:
     app.extensions = ['sympyprinting']