Rename Meteor.setPassword to Accounts.setPassword, matching docs.

We meant to do this before releasing 0.5.0 (thus the docs) but mistakenly did
not.

Fixes #454.

packages/accounts-password/password_server.js

@@ -354,7 +354,7 @@
   });
 
 
-  Meteor.setPassword = function (userId, newPassword) {
+  Accounts.setPassword = function (userId, newPassword) {
     var user = Meteor.users.findOne(userId);
     if (!user)
       throw new Meteor.Error(403, "User not found");

packages/accounts-password/password_tests.js

@@ -310,13 +310,13 @@ if (Meteor.isServer) (function () {
       test.equal(user.services.password, undefined);
 
       // set a new password.
-      Meteor.setPassword(userId, 'new password');
+      Accounts.setPassword(userId, 'new password');
       user = Meteor.users.findOne(userId);
       var oldVerifier = user.services.password.srp;
       test.isTrue(user.services.password.srp);
 
       // reset with the same password, see we get a different verifier
-      Meteor.setPassword(userId, 'new password');
+      Accounts.setPassword(userId, 'new password');
       user = Meteor.users.findOne(userId);
       var newVerifier = user.services.password.srp;
       test.notEqual(oldVerifier.salt, newVerifier.salt);