Email Verification for Add Trip

[zghera]

Issue summary

Ensure collaborator emails are in fact (potentially) valid email addresses.

Expected behavior

Use regex or some other method to determine whether or not an email address is correct. If it is not an email, show a warning to say it is not a real email address. Do not allow them to submit until this is corrected or replace any invalid emails with empty strings (these are already removed in getCollaboratorUidArr().

Actual behavior

Any string can be entered for a collaborators email as of now.