To replace incorrect location of capturing this condition in find() in
loopback-connector/lib/sql.js proposed earlier in
https://github.com/strongloop/loopback-connector/pull/34.
Being set to 'includeHasMany', findCaller option triggers injection of
PARTITION BY clause in buildColumnNames() in
loopback-connector-mssql/lib/mssql.js only when find() function is
called to process include filter with 'has many' relation.