Fixed a couple typos.
Fixed a couple typos.

I felt free to change the `filtering_expression_help` and make it less ambiguous.
ebraminio/commafeed,ahmadassaf/CommaFeed-RSS-Reader,RavenB/commafeed,RavenB/commafeed,ebraminio/commafeed,Hubcapp/commafeed,Athou/commafeed,ebraminio/commafeed,RavenB/commafeed,RavenB/commafeed,Athou/commafeed,Athou/commafeed,ahmadassaf/CommaFeed-RSS-Reader,Hubcapp/commafeed,Hubcapp/commafeed,ebraminio/commafeed,ahmadassaf/CommaFeed-RSS-Reader,Athou/commafeed,ahmadassaf/CommaFeed-RSS-Reader,Hubcapp/commafeed