apps: Set warning level to 0 for XC8

For some reason, when upgrading MPLABX, the default warning level for
at least some of the XC8 PIC18 projects defaults to -3. Change it back
to 0.

Author: signal11

apps/hid_mouse/MPLAB.X/nbproject/configurations.xml

@@ -527,6 +527,7 @@
       <HI-TECH-COMP>
         <property key="extra-include-directories"
                   value="..;../../../usb/include;../../common"/>
+        <property key="warning-level" value="0"/>
       </HI-TECH-COMP>
       <HI-TECH-LINK>
       </HI-TECH-LINK>

apps/unit_test/MPLAB.X/nbproject/configurations.xml

@@ -526,6 +526,7 @@
       <HI-TECH-COMP>
         <property key="extra-include-directories"
                   value="..;../../../usb/include;../../common"/>
+        <property key="warning-level" value="0"/>
       </HI-TECH-COMP>
       <HI-TECH-LINK>
       </HI-TECH-LINK>