(state (CO) law subjecting out-of-state retailers to sales and use notification and reporting requirements (Colo. Rev. Stat. §39-21-112(3.5)) violated Commerce Clause; permanent injunction issued; court noted that Quill Corp. v. North Dakota, 504 U.S. 298 (1992) prohibits states from imposing the same obligations on out-of-state retailers with no physical presence in the taxing jurisdiction); defendant failed to meet “very high burden of proof under the strict scrutiny standard” to overcome facial invalidity of the Colorado law”).