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.

Assistant/Threads/Watcher.hs

@@ -72,7 +72,7 @@ needLsof = error $ unlines
 
 {- A special exception that can be thrown to pause or resume the watcher. -}
 data WatcherControl = PauseWatcher | ResumeWatcher
-        deriving (Show, Eq, Typeable)
+	deriving (Show, Eq, Typeable)
 
 instance E.Exception WatcherControl