add rand, ror, rxor methods to frame
```
In [11]: s = True

In [12]: df = DataFrame(rand(10, 5)> 0.5)

In [13]: df
Out[13]:
       0      1      2      3      4
0   True  False  False   True  False
1   True  False  False   True  False
2  False  False   True  False  False
3   True  False  False   True  False
4  False  False   True   True  False
5  False  False  False   True   True
6   True   True  False   True   True
7   True   True  False  False   True
8   True   True   True   True  False
9  False  False   True  False  False

In [14]: s & df
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-14-cab092ff8433> in <module>()
----> 1 s & df

TypeError: unsupported operand type(s) for &: 'bool' and 'DataFrame'

In [15]: df & s
Out[15]:
       0      1      2      3      4
0   True  False  False   True  False
1   True  False  False   True  False
2  False  False   True  False  False
3   True  False  False   True  False
4  False  False   True   True  False
5  False  False  False   True   True
6   True   True  False   True   True
7   True   True  False  False   True
8   True   True   True   True  False
9  False  False   True  False  False
```
