Remove unnecessary trim() from home.inc.php
Show whether an invoice has been paid or not on the View Invoice screen
Tidy up Invoice->listInvoices() method
Remove ToDos from Invoice class
Add methods to Invoice class for handling editing invoices.

Work on issue #12.
Added the following methods to the Invoice class:
* getComplete()
* setComplete()
* setNotComplete()
* getSent()
* setSent()
* setNotSent()
* getPrinted()
* setPrinted()
* setNotPrinted()
* getPaid()
* setPaid()
* setNotPaid()
Work on issue #12.

Added form elements to edit invoice page.
Initialise the Client::$address property in Client->get() method
Remove unnecessary input type on invoice edit page
Update schema
More work on issue #12
Fix corrupt salt for default admin user
Merge branch 'master' into demo