Split native collector into it's component parts and make them enablable.

Last login is disabled by default as it's broken on ubuntu 12.04
Interrupts is disabled by default as it's very granular and we'll have total interrupts from /proc/stat

Allow ignoring devices from diskstats, ignore ram and loop devices by default.

Use glog for logging.

collector/helper.go

@@ -1,22 +1,11 @@
 package collector
 
 import (
-	"flag"
 	"fmt"
-	"log"
 	"strconv"
 	"strings"
 )
 
-var verbose = flag.Bool("verbose", false, "Verbose output.")
-
-func debug(name string, format string, a ...interface{}) {
-	if *verbose {
-		f := fmt.Sprintf("%s: %s", name, format)
-		log.Printf(f, a...)
-	}
-}
-
 func splitToInts(str string, sep string) (ints []int, err error) {
 	for _, part := range strings.Split(str, sep) {
 		i, err := strconv.Atoi(part)