new feature/enhancement request: new JSON string option for pandas.DataFrame.to_json()
Currently `pandas.DataFrame.to_json` supports `orient=records` which yields a file of `[{column -> value}, ... , {column -> value}]` (as a single line).  I'd like to request a slight variation of this format which is a single `{column -> value}` per line.  This yields a similar format as PostgreSQL's `row_to_json()` function.

Example of the TPC-H `region` table using `orient=records`

```
[{"r_regionkey":0,"r_name":"AFRICA","r_comment":"lar deposits. blithely final packages cajole. regular waters are final requests. regular accounts are according to "},{"r_regionkey":1,"r_name":"AMERICA","r_comment":"hs use ironic, even requests. s"},{"r_regionkey":2,"r_name":"ASIA","r_comment":"ges. thinly even pinto beans ca"},{"r_regionkey":3,"r_name":"EUROPE","r_comment":"ly final courts cajole furiously final excuse"},{"r_regionkey":4,"r_name":"MIDDLE EAST","r_comment":"uickly special accounts cajole carefully blithely close requests. carefully final asymptotes haggle furiousl"}]
```

desired new format:

```
{"r_regionkey":0,"r_name":"AFRICA","r_comment":"lar deposits. blithely final packages cajole. regular waters are final requests. regular accounts are according to "}
{"r_regionkey":1,"r_name":"AMERICA","r_comment":"hs use ironic, even requests. s"}
{"r_regionkey":2,"r_name":"ASIA","r_comment":"ges. thinly even pinto beans ca"}
{"r_regionkey":3,"r_name":"EUROPE","r_comment":"ly final courts cajole furiously final excuse"}
{"r_regionkey":4,"r_name":"MIDDLE EAST","r_comment":"uickly special accounts cajole carefully blithely close requests. carefully final asymptotes haggle furiousl"}
```
