BUG: fix read_sql delegation for queries without select statement (GH7324)
Closes #7324.

The `if 'select' in ...'` check was introduced for mysql legacy compatibility, but introduced problem if the query did not contain a select statement (eg a stored procedure). This should solve this, and passes the test suite (locally).

you mean #7324, rigtht?
 yep, changed
 should add something to release? otherwise looks good!
 yep, and maybe also a small test with a stored procedure
 added release note and test. Only problem for now is that the test is not working (see failed travis). Strange thing is that I get a `Command out of sync` error when I call `read_sql("CALL proc")` (https://github.com/jorisvandenbossche/pandas/blob/sql-delegation/pandas/io/tests/test_sql.py#L1097) after creating the procedure with `engine.execute(proc)` (which resultproxy is automatically closed by sqlalchemy). And If I run the `read_sql` a second time, it is OK. @hayd @danielballan any idea? (I can just add a `try: .. except: pass` for the first call, but that seems not really correct)
 My guess is something with transactions. I spent a few minutes today and couldn't get it. I could be wrong, but I thought I'd share that thought in case someone has more time to look at this before I revisit it.
 @danielballan Thanks for the pointer, that solved it.

I tested the following approaches:

```
engine.execute(proc)
```

```
with engine.begin() as connection:
    connection.execute(proc)
```

```
connection = engine.connect()
trans = connection.begin()
try:
    r1 = connection.execute(proc)
    trans.commit()
except:
    trans.rollback()
    raise
```

And only the last did work, although I don't fully understand why, as I would think the other should be equivalent (http://docs.sqlalchemy.org/en/rel_0_8/core/connections.html#using-transactions), as sqlalchemy autocommits by default. But in any case, it works now (and it was only for the test, so not that important).
