Colorado medical marijuana advocates and a group of local veterans filed a petition with the state health department yesterday that would add post-traumatic stress disorder to the list of qualifying conditions for medical marijuana in Colorado. The petition was formally filed by Army veteran and double amputee Kevin Grimsinger, who lost parts of both legs and suffered other injuries after stepping on a landmine in Afghanistan in 2001. That episode has also left him stricken with PTSD. From Denver…