Subsubsribing

See merge request !7

 Fixing the bugs in signup Lab creation, adding Professor DTO to Postings and updating labname to labID

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update posting to use lab id instead of labName string
update security config to add api/postings/**

add /email/{email} for professor user

add GET for finding student by email, since email is stored upon login on front end - best way to get the user details.

uncommented some seed.sql for testing

Api edits

See merge request !5

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