Clean up IsWindows check, add hasProc check

Patch by Blake Eggleston; reviewed by jmckenzie for CASSANDRA-8452
Merge branch 'cassandra-2.1' into trunk

Conflicts:
	src/java/org/apache/cassandra/service/StorageService.java
	src/java/org/apache/cassandra/utils/FBUtilities.java
merge fixes for CASSANDRA-8452