By Piya Sinha-Roy LOS ANGELES (Reuters) – Meghan McCain, who gained attention in 2007 for her lively blogs tracking her father John McCain's presidential campaign, is bringing her "brand of Republicanism" to a new television show she hopes will change perceptions of the millennial generation. McCain, 28, is the face of "Raising McCain" that premieres on Saturday on new cable channel Pivot TV, with the aim of presenting a different take on the challenges and issues facing young people. …