mssql - query-generator isn't setting its dialect key

Unlike other dialects, mssql isn't setting:
```
dialect:  'mssql'
```
in its QueryGenerator definition.  This causes, for example, boolean values to be translated incorrectly.  Without this fix, bools become literal true/false values in the generated SQL queries, which mssql does not support.  With this fix, bools are correctly translated to 0/1 in the generated SQL.