tests: Expand Stored Procedure invocation tests.
tests: Expand Stored Procedure invocation tests.

- Show it's also possible to call SPs with output parameters by using
  the helper pymssql.putput class.
- Show it's possible to fetch results of queries performed by SPs
  both from _mssql and pymssql.

zerolugithub/pymssql,JimDennis/pymssql,JimDennis/pymssql,Aloomaio/pymssql,zerolugithub/pymssql,bladams/pymssql,bladams/pymssql,ramiro/pymssql,Aloomaio/pymssql,JimDennis/pymssql,pymssql/pymssql,ramiro/pymssql,ramiro/pymssql,bladams/pymssql,pymssql/pymssql,zerolugithub/pymssql,klothe/pymssql,klothe/pymssql,klothe/pymssql,Aloomaio/pymssql