ENH: multiindex formatting
closes #12423

```
In [1]: pd.options.display.width=80

In [2]: pd.options.display.max_seq_items=10

In [3]: pd.options.display.max_seq_items=100

In [4]:         mi = pd.MultiIndex.from_tuples([('A', 1), ('A', 2),
                                        ('B', 3), ('B', 4)])

In [5]: mi
Out[5]: 
MultiIndex(levels=[[u'A', u'B'],
                   [1, 2, 3, 4]],
           labels=[[0, 0, 1, 1],
                   [0, 1, 2, 3]])

In [6]:         mi = MultiIndex.from_product([list('abcdefg'),
                                      range(10),
                                      pd.date_range('20130101', periods=10)],
                                     names=['first', 'second', 'third'])

In [7]: mi
Out[7]: 
MultiIndex(levels=[[u'a', u'b', u'c', u'd', u'e', u'f', u'g'],
                   [0, 1, 2, 3, 4, 5, 6, 7, 8, 9],
                   ['2013-01-01', '2013-01-02', '2013-01-03', '2013-01-04', '2013-01-05', '2013-01-06', '2013-01-07', '2013-01-08', '2013-01-09', '2013-01-10']],
           labels=[[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
                    ...
                    6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6],
                   [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2,
                    ...
                    7, 7, 7, 7, 7, 8, 8, 8, 8, 8, 8, 8, 8, 8, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9],
                   [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4,
                    ...
                    5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9]],
           names=[u'first', u'second', u'third'])

```
