Indicate that usbmuxd is a runtime dependency

Fixes: libimobiledevice#91

README.md

@@ -17,6 +17,9 @@ Some key features are:
 
 ## Installation / Getting started
 
+Please note that `usbmuxd` must also be installed. `ifuse` will not be able to
+communicate with devices without it.
+
 ### Debian / Ubuntu Linux
 
 First install all required dependencies and build tools:

src/ifuse.c

@@ -820,7 +820,7 @@ int main(int argc, char *argv[])
 		} else {
 			printf("ERROR: No device found!\n");
 		}
-		fprintf(stderr, "Is the device properly connected?\n");
+		fprintf(stderr, "Ensure that the device properly connected and usbmuxd is installed.\n");
 		fprintf(stderr, "If it is make sure that your user has permissions to access the raw USB device.\n");
 		fprintf(stderr, "If you're still having issues try unplugging the device and reconnecting it.\n");
 		return EXIT_FAILURE;