add inode cache to the db

Renamed the db to keys, since it is various info about a Keys.

Dropping a key will update its pointer files, as long as their content can
be verified to be unmodified. This falls back to checksum verification, but
I want it to use an InodeCache of the key, for speed. But, I have not made
anything populate that cache yet.

Annex.hs

@@ -60,7 +60,7 @@ import Types.NumCopies
 import Types.LockCache
 import Types.DesktopNotify
 import Types.CleanupActions
-import qualified Database.AssociatedFiles.Types
+import qualified Database.Keys.Types
 #ifdef WITH_QUVI
 import Utility.Quvi (QuviVersion)
 #endif
@@ -135,7 +135,7 @@ data AnnexState = AnnexState
 	, desktopnotify :: DesktopNotify
 	, workers :: [Either AnnexState (Async AnnexState)]
 	, concurrentjobs :: Maybe Int
-	, associatedfilesdbhandle :: Maybe Database.AssociatedFiles.Types.DbHandle
+	, keysdbhandle :: Maybe Database.Keys.Types.DbHandle
 	}
 
 newState :: GitConfig -> Git.Repo -> AnnexState
@@ -181,7 +181,7 @@ newState c r = AnnexState
 	, desktopnotify = mempty
 	, workers = []
 	, concurrentjobs = Nothing
-	, associatedfilesdbhandle = Nothing
+	, keysdbhandle = Nothing
 	}
 
 {- Makes an Annex state object for the specified git repo.