PACHUCA, Mexico — A community project in central Mexico is bringing art to people’s homes. A group of artists known as the Germ Collective have spent 14 months turning the hillside neighborhood of Las Palmitas into a giant, colorful mural in an effort to bring the working-class “barrio” together and change its gritty image. Working hand-in-hand with residents, muralists have painted the facades of 200 homes bright lavender, lime green, incandescent orange — hues more commonly found in a bag of Skittles than in the drab, concrete-and-cinderblock neighborhoods where many of Mexico’s poor live.