improve docs, CLDR is optional

If CLDR.pluralForm is not defined, Em.I18n will not inflect based on
count.

README.md

@@ -4,13 +4,17 @@ Internationalization for Ember
 
 ### Requirements
 
-The [CLDR.js pluralization library](https://github.com/jamesarosen/CLDR.js).
+Set `Em.I18n.translations` to an object containing your translation
+information. If you want to support inflection based on `count`, you will
+also need to include the
+[CLDR.js pluralization library](https://github.com/jamesarosen/CLDR.js)
+and set `CLDR.defaultLocale` to the current locale code (e.g. "de").
 
 ### Examples
 
 Given
 
-    I18n.translations = {
+    Em.I18n.translations = {
       'user.edit.title': 'Edit User',
       'user.followers.title.one': 'One Follower',
       'user.followers.title.other': 'All {{count}} Followers',

lib/i18n.coffee

@@ -6,7 +6,7 @@ getPath = Ember.Handlebars.getPath || Ember.getPath
 
 pluralForm = CLDR.pluralForm if CLDR?
 
-ember_assert("Could not find CLDR.pluralForm. You can find it at https://github.com/jamesarosen/CLDR.js", pluralForm?)
+Ember.Logger.warn "CLDR.pluralForm not found. Em.I18n will not support count-based inflection." unless pluralForm?
 
 findTemplate = (key, setOnMissing) ->
   ember_assert("You must provide a translation key string, not %@".fmt(key), typeof key is 'string')
@@ -23,7 +23,7 @@ I18n = {
   translations: {}
 
   template: (key, count) ->
-    if count?
+    if count? && pluralForm?
       suffix = pluralForm count
       interpolatedKey = "%@.%@".fmt key, suffix
       result = findTemplate(interpolatedKey, false)