2.11.0-M8 announcement

created from https://github.com/scala/make-release-notes/tree/v2.11.0-M8, with:

```
sbt -Dfile.encoding=UTF-8 console
scala> MakeReleaseNotes.genPR("2.11.0-M7", "2.11.0-M8", "2014/01/28")
```

sanity checked (after `sudo gem install maruku`):
`maruku --html 2014-01-28-release-notes-2.11.0-M8.md`

ready to be merged -- review by @sjrd or @heathermiller