Fix Cayley table doctest failure in group theory tutorial

[rbeezer]

On 32-bit Suse I build 4.4.1.alpha2 fine and get just one error in a new tutorial:

sage -t  devel/sage/doc/en/thematic_tutorials/group_theory.rst
**********************************************************************
File "/local/jec/sage-4.4.1.alpha2/devel/sage-main/doc/en/thematic_tutorials/group_theory.rst",
line 432:
    sage: H.cayley_table()
Expected:
    [ x0  x1  x2  x3  x4  x5  x6  x7  x8  x9 x10 x11]
    [ x1  x0  x3  x2  x5  x4  x7  x6  x9  x8 x11 x10]
    [ x2 x10  x0  x4  x3  x6  x5  x8  x7 x11  x1  x9]
    [ x3 x11  x1  x5  x2  x7  x4  x9  x6 x10  x0  x8]
    [ x4  x9 x10  x6  x0  x8  x3 x11  x5  x1  x2  x7]
    [ x5  x8 x11  x7  x1  x9  x2 x10  x4  x0  x3  x6]
    [ x6  x7  x9  x8 x10 x11  x0  x1  x3  x2  x4  x5]
    [ x7  x6  x8  x9 x11 x10  x1  x0  x2  x3  x5  x4]
    [ x8  x5  x7 x11  x9  x1 x10  x2  x0  x4  x6  x3]
    [ x9  x4  x6 x10  x8  x0 x11  x3  x1  x5  x7  x2]
    [x10  x2  x4  x0  x6  x3  x8  x5 x11  x7  x9  x1]
    [x11  x3  x5  x1  x7  x2  x9  x4 x10  x6  x8  x0]
Got:
    *  a b c d e f g h i j k l
     +------------------------
    a| a b c d e f g h i j k l
    b| b a d c f e h g j i l k
    c| c k a e d g f i h l b j
    d| d l b f c h e j g k a i
    e| e j k g a i d l f b c h
    f| f i l h b j c k e a d g
    g| g h j i k l a b d c e f
    h| h g i j l k b a c d f e
    i| i f h l j b k c a e g d
    j| j e g k i a l d b f h c
    k| k c e a g d i f l h j b
    l| l d f b h c j e k g i a
    <BLANKLINE>
**********************************************************************

which looks trivial.

John 

[mvngu]

This ticket really depends on merging the patch at #8468, which has its own prerequisites. But since this ticket is merged in Sage 4.4.1.alpha3, it has messed up the dependencies in #8468. What we can do now is close #8468. The other tickets relating to the thematic tutorials can be dealt with later.