Do not save config keys that still have the default value
Do not save config keys that still have the default value

This way mce package upgrade can change config keys that the
user has not explicitly set to non-default value.

mikkoharju/mce,mlehtima/mce,spiiroin/mce,mikkoharju/mce,kimmoli/mce,maikelwever/mce,kimmoli/mce,android-808/mce,android-808/mce,kimmoli/mce,spiiroin/mce,mlehtima/mce,maikelwever/mce,kimmoli/mce,mlehtima/mce,spiiroin/mce,spiiroin/mce,mikkoharju/mce,mlehtima/mce,maikelwever/mce,mikkoharju/mce,maikelwever/mce,android-808/mce,android-808/mce