Version 4.0.2

Fixed bug with login initiation requests using HTTP GET
Correct date format used in data connector for MS SQL Server
Try retreiving public key from URL if stored value fails
Save LTI user ID for all learners
Leeway used when checking timestamps in JWTs is now configurable
Tries to request access token with single scope if request for multiple scopes is declined
Update isAdmin check for LTI 1.3 format
Other minor bug fixes and general code tidy