Suits and sneakers: get any mom-on-the-train connotations out of your mind, pronto — this is the now-est way to wear tailoring; a combination that is equal parts smart and sass. Kristen Stewart is the ultimate suits and sneakers pin-up, with her DGAF attitude summing up the essence of this style. So if you want to make this grungy '90s look your thing in 2015, pay close attention to how she and bloggers Rebecca Laurey and Trine Kjaer do it…