ENH : Allow to_sql to recognize single sql type #11886
Continued in #13252 

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This solves #11886 
It checks whether the passed dtype variable is a dictionary.
If not, it creates a new dictionary with keys as the columns of the dataframe.
It then passes this dictionary  to the pandasSQL_builder.

tests!
 Update: Writing the tests has been more difficult that I thought it would be. I am currently working on it though.
 @RahulHP For the test, best have a look at the existing `test_dtype` test (https://github.com/RahulHP/pandas/blob/to_sql-dictionary/pandas/io/tests/test_sql.py#L1502). You can see there how it is checked that the dtype is actually used in the database. 
And maybe you can just add your test to that function.
 Update: I added the new test and it passes the Travis build.
 Edits done
 can you rebase / squash
 Done, I followed the Contributing guide as best as I could but I think I may have messed it up.
 @RahulHP There indeed slipped in some changes from other PRs. Normally, by doing exactly this, it should be solved:

```
git checkout to_sql-dictionary
git fetch upstream
git rebase upstream/master
git push -f origin to_sql-dictionary
```

In the rebase step, you will possibly need to resolve some conflicts
 can you rebase/update
 Sorry, I'll work on this in a few days.
 pls rebase / update
 I have created a new pull request here https://github.com/pydata/pandas/pull/13252
