* Sworn in 18 months after coup, rebel uprising
* Promises to make peace with Tuareg rebels
* Faces challenge of reviving economy
By Tiemoko Diallo and Adama Diarra
BAMAKO, Sept 4 (Reuters) - Mali's new president, Ibrahim Boubacar Keita, pledged to stamp out corruption and bring peace to the turbulent north as he was sworn in on Wednesday, 18 months after a coup and rebel uprising ...