be stricter about rejecting invalid configurations for remotes

This is a first step toward that goal, using the ProposedAccepted type
in RemoteConfig lets initremote/enableremote reject bad parameters that
were passed in a remote's configuration, while avoiding enableremote
rejecting bad parameters that have already been stored in remote.log

This does not eliminate every place where a remote config is parsed and a
default value is used if the parse false. But, I did fix several
things that expected foo=yes/no and so confusingly accepted foo=true but
treated it like foo=no. There are still some fields that are parsed with
yesNo but not not checked when initializing a remote, and there are other
fields that are parsed in other ways and not checked when initializing a
remote.

This also lays groundwork for rejecting unknown/typoed config keys.

Command/RenameRemote.hs

@@ -13,6 +13,7 @@ import Annex.SpecialRemote.Config (nameField, sameasNameField)
 import qualified Logs.Remote
 import qualified Types.Remote as R
 import qualified Remote
+import Types.ProposedAccepted
 
 import qualified Data.Map as M
 
@@ -50,6 +51,6 @@ perform u cfg mcu newname = do
 	let (namefield, cu) = case mcu of
 		Nothing -> (nameField, u)
 		Just (Annex.SpecialRemote.ConfigFrom u') -> (sameasNameField, u')
-	Logs.Remote.configSet cu (M.insert namefield newname cfg)
+	Logs.Remote.configSet cu (M.insert namefield (Proposed newname) cfg)
 	
 	next $ return True