Update README to advise people not to start new projects with compass

Compass' merged PR Compass/compass#2094 is a clear indication that compass is no longer supported.

Author: aCandidMind

README.md

@@ -1,5 +1,7 @@
 # compass-rails
 
+**Don't start new projects with compass, it is no longer supported, see the [compass statement](https://github.com/Compass/compass/pull/2094)**
+
 **We Take Pull Requests!**
 
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