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.

Command/Fsck.hs

@@ -282,7 +282,7 @@ verifyDirectMode key file = do
  - the key's metadata, if available.
  -
  - Not checked in direct mode, because files can be changed directly.
-  -}
+ -}
 checkKeySize :: Key -> Annex Bool
 checkKeySize key = ifM isDirect
 	( return True