API: allow Series comparison ops to align before comparison (GH1134)

closes #1134

reordered comparisons

```
In [1]:     s1 = Series(index=["A", "B", "C"], data=[1,2,3])

In [2]:      s1
Out[2]: 
A    1
B    2
C    3
dtype: int64

In [3]:      s2 = Series(index=["C", "B", "A"], data=[3,2,1])

In [4]:      s2
Out[4]: 
C    3
B    2
A    1
dtype: int64

In [5]:      s1 == s2
Out[5]: 
A    True
B    True
C    True
dtype: bool
```

Here we have a missing value, so it's ``nan`` in the comparisons
```
In [6]:      s3 = Series(index=["C", "B"], data=[3,2])

In [7]:      s3
Out[7]: 
C    3
B    2
dtype: int64

In [8]:      s1 == s3
Out[8]: 
A    False
B     True
C     True
dtype: bool

In [9]: s1>s3
Out[9]: 
A    False
B    False
C    False
dtype: bool

In [10]: s1<s3
Out[10]: 
A    False
B    False
C    False
dtype: bool
```