Fixes #97 - Use nproc command to count cores

The nproc command should be available on most Linux distros and
can replace the `cores` method in riemann-health.

This should address issues where a host has multiple cores with the
same ID.

bin/riemann-health

@@ -39,7 +39,7 @@ class Riemann::Tools::Health
       @load = method :freebsd_load
       @memory = method :freebsd_memory
     else
-      @cores = cores
+      @cores = `nproc`.to_i
       puts "WARNING: OS '#{@ostype}' not explicitly supported. Falling back to Linux" unless @ostype == "linux"
       @cpu = method :linux_cpu
       @disk = method :disk
@@ -70,23 +70,6 @@ class Riemann::Tools::Health
     )
   end
 
-  def cores
-    i = 0;
-    File.read("/proc/cpuinfo").split(/\n\n/).inject({}) do |cores, p|
-      physical_id = p[/physical id\s+:\s+(\d+)/, 1]
-      core_id = p[/core id\s+:\s+(\d+)/, 1]
-      if physical_id and core_id
-        cores["#{physical_id}:#{core_id}"] = true
-      elsif physical_id
-        cores["#{physical_id}:"] = true
-      else
-        cores[i += 1] = true;
-      end
-
-      cores
-    end.size
-  end
-
   def report_pct(service, fraction, report)
     if fraction
       if fraction > @limits[service][:critical]