[FIX] hw_escpos: certain Epson printers do not identify as a printer

We search for USB devices that identify as a printer through their
DeviceClass or one of their InterfaceClasses. The issue is a lot of
printers use vendor-specific Device/InterfaceClasses.

Apparently the Epson TM-T88IV is one of those devices. So in order to
work around this, we now first look for a USB device that identifies as
a printer. If those do not exist, we pick the first Epson device, if
those do not exist we pick the first Star device.

Perhaps we should instead start using some kind of probe-based approach
to identify ESC/POS compatible devices.

addons/hw_escpos/controllers/main.py

@@ -76,11 +76,12 @@ class EscposDriver(Thread):
 
         printers = usb.core.find(find_all=True, custom_match=FindUsbClass(7))
 
-        # Currently we ask customers to put the STAR TSP650II into
-        # 'USB Mode' Vendor class instead of Printer class. When set
-        # to Printer class it doesn't show up under Linux at
-        # all. Vendor class does work, but that means that it's not
-        # going to have an interfaceClass 7.
+        # if no printers are found after this step we will take the
+        # first epson or star device we can find.
+        # epson
+        if not printers:
+            printers = usb.core.find(find_all=True, idVendor=0x04b8)
+        # star
         if not printers:
             printers = usb.core.find(find_all=True, idVendor=0x0519)