Added profile page, technician sign-up, foreign-key relationships, and issue assignment. Closes #1 Closes #7 Closes #8

[lcnorine]

Note that I changed the database models somewhat significantly. Consider deleting old db/migrations to test, though I tried to keep default values/null replacement if foreign keys did not exist where it made sense.

[CodeMastr3]

Well done expanding on the models and putting some actual usability to them