Disable OutConnectionString in SQLDriverConnect

We weren't using it anyway and it was an extra malloc
Use Local<Object> instead of Persisten<Object> for ODBC* instances
Use proper HDBC type when getting js_hdbc->Value()
Set connected status after closeSync()
statement: free SQL_C_WCHAR param types
statement: throw errors on prepareSync
test: add test to try to invoke errors during prepare/bind/execute
Set the prototype of our error objects to Exception::Error

This allows node's default error handling to display stack
traces and such. So much nicer than just [Object object]
Don't set message manually on error object, use Exception::Error constructor for that
test: update test to assert throw/doesNotThrow
0.5.21