Add users to companies based on their email (suffix)

Add option to automatically approve users to companies based on their email suffix.

• Multiple suffixes must be specifiable per company
• The suffix is always the part after the @
• Server side blacklisting of common email providers (icloud, gmail, hotmail, outlook, tudelft, *.tudelft, ...) (Look up public email providers) https://gist.github.com/technikhil314/67d82ecf2beb633571064119d1f6e92d