indent with tabs not spaces

Found these with:
git grep "^  " $(find -type  f -name \*.hs) |grep -v ':  where'

Unfortunately there is some inline hamlet that cannot use tabs for
indentation.

Also, Assistant/WebApp/Bootstrap3.hs is a copy of a module and so I'm
leaving it as-is.

Build/Standalone.hs

@@ -40,7 +40,7 @@ main :: IO ()
 main = getArgs >>= go
   where
 	go [] = error "specify topdir"
-        go (topdir:_) = do
+	go (topdir:_) = do
 		let dir = progDir topdir
 		createDirectoryIfMissing True dir
 		installed <- forM bundledPrograms $ installProg dir