Tweak #message feedback colors once more.

- Mute neon yellow for generic #message
- Make #message.error background red
- Make #message.updated font darker

See r7246 for accompanying commit.

git-svn-id: https://buddypress.svn.wordpress.org/trunk@7272 cdf35c40-ae34-48e0-9cc9-0c9da1808c22