Resolves Jira issue OE-798
Resolves Jira issue OE-798

Added an alertBox banner stating that a greyed out session cannot be booked into as it's in the past.

FiviumAustralia/OpenEyes,FiviumAustralia/OpenEyes,FiviumAustralia/OpenEyes,FiviumAustralia/OpenEyes,FiviumAustralia/OpenEyes