[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")
```

- [ ] Travis CI PostgreSQL Testing
- [ ] Travis CI MySQL Testing

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I agree.  I don't like it.  We could instead use `sqlalchemy.types.Text` instead of String.  `Text` is use in both:
- [Postgres](http://www.postgresql.org/docs/9.1/static/datatype-character.html)
- [MySql](http://dev.mysql.com/doc/refman/5.0/en/string-type-overview.html)