matrices: add test for args
matrices: add test for args

There is a disturbing feature that ImmutableSparseMatrix needs rows and cols
to be defined in the _new method. Here is a record of what happens when
other things are tried:

If I don't assign rows (for example) in the `__init__` then tests fail

```
_______________ sympy/matrices/tests/test_matrices.py:test_cross _______________
  File "/sympy/sympy/matrices/tests/test_matrices.py", line 1971, in test_cross
    test(A.cross(B))
  File "/sympy/sympy/matrices/tests/test_matrices.py", line 1966, in test
    assert ans == M
AssertionError

________________________________________________________________________________
______________ sympy/matrices/tests/test_matrices.py:test_adjoint ______________
  File "/sympy/sympy/matrices/tests/test_matrices.py", line 1996, in test_adjoint
    assert ans == cls(dat).adjoint()
AssertionError
```

And if I put a print statement in the test_cross I get

```
  File "/sympy/sympy/matrices/tests/test_matrices.py", line 1972, in test_cross
    test(A.cross(B))
  File "/sympy/sympy/matrices/tests/test_matrices.py", line 1966, in test
    print type(ans), type(M), M.rows
  File "sympy/matrices/matrices.py", line 2806, in __getattr__
    raise AttributeError("%s has no attribute %s." % (self.__class__.__name__, attr))
AttributeError: ImmutableSparseMatrix has no attribute rows.
```
And that's weird because the `test_args` test (which tests for rows and cols) *passes*.

If I write it as a property like this

```
    @property
    def rows(self):
        return int(self.args[0])
```

I get a complaint from Sparse:

```
  File "sympy/matrices/tests/test_matrices.py", line 1970, in test_cross
    A = cls(a)
  File "sympy/matrices/sparse.py", line 85, in __init__
    self.rows = r
AttributeError: can't set attribute
```

So...I don't understand what is going on. What is there works but it
probably can be done in some better way.

cswiercz/sympy,grevutiu-gabriel/sympy,pandeyadarsh/sympy,meghana1995/sympy,toolforger/sympy,wyom/sympy,Shaswat27/sympy,amitjamadagni/sympy,hargup/sympy,AunShiLord/sympy,kaushik94/sympy,ga7g08/sympy,chaffra/sympy,dqnykamp/sympy,dqnykamp/sympy,saurabhjn76/sympy,beni55/sympy,Davidjohnwilson/sympy,drufat/sympy,jbbskinny/sympy,iamutkarshtiwari/sympy,postvakje/sympy,asm666/sympy,hargup/sympy,rahuldan/sympy,toolforger/sympy,Designist/sympy,bukzor/sympy,mafiya69/sympy,cswiercz/sympy,ChristinaZografou/sympy,rahuldan/sympy,saurabhjn76/sympy,mafiya69/sympy,Vishluck/sympy,MechCoder/sympy,jamesblunt/sympy,mcdaniel67/sympy,aktech/sympy,jaimahajan1997/sympy,pandeyadarsh/sympy,wanglongqi/sympy,chaffra/sympy,bukzor/sympy,debugger22/sympy,yukoba/sympy,hrashk/sympy,jaimahajan1997/sympy,kmacinnis/sympy,atreyv/sympy,Vishluck/sympy,garvitr/sympy,shipci/sympy,Mitchkoens/sympy,VaibhavAgarwalVA/sympy,ga7g08/sympy,iamutkarshtiwari/sympy,Arafatk/sympy,hargup/sympy,liangjiaxing/sympy,yashsharan/sympy,kaichogami/sympy,kumarkrishna/sympy,VaibhavAgarwalVA/sympy,sahilshekhawat/sympy,kumarkrishna/sympy,amitjamadagni/sympy,madan96/sympy,garvitr/sympy,jbbskinny/sympy,oliverlee/sympy,ChristinaZografou/sympy,lidavidm/sympy,cccfran/sympy,jbbskinny/sympy,sahilshekhawat/sympy,Arafatk/sympy,abhiii5459/sympy,souravsingh/sympy,kevalds51/sympy,drufat/sympy,ahhda/sympy,meghana1995/sympy,jerli/sympy,emon10005/sympy,jamesblunt/sympy,hrashk/sympy,oliverlee/sympy,atsao72/sympy,madan96/sympy,Designist/sympy,aktech/sympy,souravsingh/sympy,wanglongqi/sympy,liangjiaxing/sympy,sunny94/temp,aktech/sympy,Titan-C/sympy,skidzo/sympy,MechCoder/sympy,Curious72/sympy,kevalds51/sympy,sahilshekhawat/sympy,maniteja123/sympy,asm666/sympy,moble/sympy,atsao72/sympy,souravsingh/sympy,cccfran/sympy,MridulS/sympy,grevutiu-gabriel/sympy,lindsayad/sympy,farhaanbukhsh/sympy,yukoba/sympy,sunny94/temp,Sumith1896/sympy,sampadsaha5/sympy,Gadal/sympy,abhiii5459/sympy,ga7g08/sympy,ahhda/sympy,liangjiaxing/sympy,Curious72/sympy,sahmed95/sympy,AkademieOlympia/sympy,beni55/sympy,kaichogami/sympy,Curious72/sympy,bukzor/sympy,shikil/sympy,beni55/sympy,chaffra/sympy,sampadsaha5/sympy,yashsharan/sympy,maniteja123/sympy,vipulroxx/sympy,sunny94/temp,skidzo/sympy,jerli/sympy,wanglongqi/sympy,Arafatk/sympy,asm666/sympy,debugger22/sympy,vipulroxx/sympy,ahhda/sympy,Titan-C/sympy,shikil/sympy,mcdaniel67/sympy,Davidjohnwilson/sympy,kumarkrishna/sympy,AkademieOlympia/sympy,meghana1995/sympy,wyom/sympy,abloomston/sympy,postvakje/sympy,madan96/sympy,skirpichev/omg,cccfran/sympy,Titan-C/sympy,atreyv/sympy,AunShiLord/sympy,MechCoder/sympy,diofant/diofant,postvakje/sympy,maniteja123/sympy,lindsayad/sympy,iamutkarshtiwari/sympy,mafiya69/sympy,kmacinnis/sympy,farhaanbukhsh/sympy,vipulroxx/sympy,hrashk/sympy,moble/sympy,VaibhavAgarwalVA/sympy,Davidjohnwilson/sympy,Mitchkoens/sympy,jaimahajan1997/sympy,kmacinnis/sympy,Shaswat27/sympy,shipci/sympy,Gadal/sympy,Sumith1896/sympy,moble/sympy,emon10005/sympy,AunShiLord/sympy,saurabhjn76/sympy,oliverlee/sympy,pbrady/sympy,shipci/sympy,pbrady/sympy,skidzo/sympy,farhaanbukhsh/sympy,emon10005/sympy,yukoba/sympy,jerli/sympy,grevutiu-gabriel/sympy,sahmed95/sympy,pbrady/sympy,MridulS/sympy,abloomston/sympy,abloomston/sympy,drufat/sympy,Vishluck/sympy,wyom/sympy,Gadal/sympy,lidavidm/sympy,AkademieOlympia/sympy,abhiii5459/sympy,kaushik94/sympy,shikil/sympy,Designist/sympy,debugger22/sympy,jamesblunt/sympy,lindsayad/sympy,rahuldan/sympy,kevalds51/sympy,pandeyadarsh/sympy,kaichogami/sympy,sampadsaha5/sympy,cswiercz/sympy,atreyv/sympy,Mitchkoens/sympy,ChristinaZografou/sympy,dqnykamp/sympy,lidavidm/sympy,garvitr/sympy,Shaswat27/sympy,Sumith1896/sympy,yashsharan/sympy,mcdaniel67/sympy,toolforger/sympy,kaushik94/sympy,atsao72/sympy,sahmed95/sympy,MridulS/sympy