Comcast Corp. , fulfilling one of the promises it made when it sought approval for its acquisition of a controlling stake in NBC Universal, said Tuesday it would launch four minority-owned independent networks that will be seen on Comcast Cable systems beginning in April. ReutersEarvin “Magic” Johnson playing for the Los Angeles Lakers in 1996. The channels include Aspire, run by former Los Angeles Lakers star Magic Johnson, Revolt, led by Sean “P. Diddy” Combs and MTV veteran Andy Schuon; El Rey, a network offering action-oriented content to Latino and general audiences; and BabyFirst Americas, aimed at infants, young children...