[WIP] Feature/csv to sql natively

When finished, this PR should address #352. New `into` function calls out to to native COPY function of various DBs.  Has optional `if_exists` argument (similar to pandas) to handle three cases: replace, append, and fail

```python
into(sql,csv, if_exists="replace")
```


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It would be nice also to support the terms used by csv dialects

```Python
In [1]: import csv

In [2]: d = csv.get_dialect('excel')

In [3]: d.
d.delimiter         d.lineterminator    d.skipinitialspace
d.doublequote       d.quotechar         d.strict
d.escapechar        d.quoting           
```

As well as `sep` as used by Pandas.  Perhaps data/csv.py should have a mapping of terms to some normalized form like 

```Python
dialect_terms = {'delimiter': 'delimter', 'DELIMITER': 'delimiter', 'sep': 'delimiter', ...} 
```