Fix PHP Warning on user login

While at it, I also extracted the hash function into it's own getHash
method. This will allow easy changes to hashing for string in the
future.

Fixes #382
Change message on empty donor list

This fixes #380.
Merge pull request #385 from TheSerapher/issue-382

Fix PHP Warning on user login
Merge pull request #386 from TheSerapher/issue-380

Change message on empty donor list
Merge pull request #7 from TheSerapher/next

Next