Rename helper packages

crypto/crypto.go

duration/LICENSE

duration/duration.go

duration/duration_test.go

http/client.go

locale/translations.go

reader/atom/atom.go

reader/feed/handler.go

reader/feed/parser.go

reader/icon/finder.go

reader/json/json.go

reader/rdf/rdf.go

reader/rss/rss.go

reader/subscription/finder.go

server/core/context.go

server/core/handler.go

server/template/common.go

server/template/template.go

server/template/views.go

server/ui/controller/proxy.go