add "mssql" driver name as synonym for "sqlsrv"
Merge branch 'master' of https://github.com/ndunand/moodle-tool_mergeusers
tool_mergeusers: Correct QuizAttemptsMerger SQL for mssql, correctness
Merge pull request #71 from MorrisR2/correct_attempts_merger_sql

Correct attempts merger sql