mssql - query-generator.js didn't set its own dialect property

Unlike other dialects, mssql’s query-generator.js didn’t set its
‘dialect’ key in its QueryGenerator declaration.

Most visible side-effect of this was that booleans would be translated
to true/false literals - but mssql uses 0/1 for booleans.

This change fixes that (and also contains my earlier escaping fix)
Merge pull request #1425 from displaced/mssql-boolfix

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