Fix series comparison operators when dealing with zero rank numpy arrays
- [x] closes #13006
- [x] tests added / passed
- [x] passes `git diff upstream/master | flake8 --diff`
- [x] whatsnew entry

http://stackoverflow.com/questions/4565749/how-detect-length-of-a-numpy-array-with-only-one-element#4565910

Partially based on @sldion 's changes. Thanks
 ## [Current coverage](https://codecov.io/gh/pydata/pandas/pull/13307?src=pr) is **84.22%**

> Merging [#13307](https://codecov.io/gh/pydata/pandas/pull/13307?src=pr) into [master](https://codecov.io/gh/pydata/pandas/branch/master?src=pr) will decrease coverage by **<.01%**

``` diff
@@             master     #13307   diff @@
==========================================
  Files           138        138          
  Lines         50721      50667    -54   
  Methods           0          0          
  Messages          0          0          
  Branches          0          0          
==========================================
- Hits          42723      42673    -50   
+ Misses         7998       7994     -4   
  Partials          0          0          
```

> Powered by [Codecov](https://codecov.io?src=pr). Last updated by [0c6226c...b49a116](https://codecov.io/gh/pydata/pandas/compare/0c6226cbbc319ec22cf4c957bdcc055eaa7aea99...b49a11685293cd98616c55160675a01be7c2343b)
 @jreback Are you good with this PR? Thanks
 build is green
 thanks @gliptak 
