So, it’s kind of a slow week for music in D.C. Labor Day weekend is beckoning, 9:30 is dark most of the week, and Black Cat is closed for a few days to make repairs. But give DCist lemons, and DCist makes lemonade, unearthing these gems for this last week of August. MONDAY: >> The early 1990s were full of quasi-generic melodic soft rock acts. We won’t say that Toad the Wet Sprocket stood head…