Table-valued parameters

Support for tuples as input. Limitations are the same as mentioned in issue #23:

* Need to send parameter to a stored procedure or UDF.
* Table must be predefined using `CREATE TYPE`

I added a sample to the readme. 

To be able to test this, I added a dependency on AdventureWorks2012 in TypeProvider.Test.fs. I hope this is okay.
AdventureWorks2012 doesn't have any user-defined table types or sprocs for working with them, so I needed to add some. They are in prereqs.sql.