Make collector-specific flags consistent with others.

This puts all collector-specific flags into their own namespace under
"collector.<collector-name>", and moves from camel case to dashes, which
is the standard in Prometheus land now.

collector/diskstats.go

@@ -22,7 +22,7 @@ const (
 )
 
 var (
-	ignoredDevices = flag.String("diskstatsIgnoredDevices", "^(ram|loop|fd|(h|s|v|xv)d[a-z])\\d+$", "Regexp of devices to ignore for diskstats.")
+	ignoredDevices = flag.String("collector.diskstats.ignored-devices", "^(ram|loop|fd|(h|s|v|xv)d[a-z])\\d+$", "Regexp of devices to ignore for diskstats.")
 )
 
 type diskstatsCollector struct {

collector/filesystem.go

@@ -21,7 +21,7 @@ const (
 )
 
 var (
-	ignoredMountPoints = flag.String("filesystemIgnoredMountPoints", "^/(sys|proc|dev)($|/)", "Regexp of mount points to ignore for filesystem collector.")
+	ignoredMountPoints = flag.String("collector.filesystem.ignored-mount-points", "^/(sys|proc|dev)($|/)", "Regexp of mount points to ignore for filesystem collector.")
 )
 
 type filesystemCollector struct {

collector/ntp.go

@@ -13,7 +13,7 @@ import (
 )
 
 var (
-	ntpServer = flag.String("ntpServer", "", "NTP server to use for ntp collector.")
+	ntpServer = flag.String("collector.ntp.server", "", "NTP server to use for ntp collector.")
 )
 
 type ntpCollector struct {

collector/textfile.go

@@ -20,7 +20,7 @@ import (
 )
 
 var (
-	textFileDirectory = flag.String("textfile.directory", "", "Directory to read text files with metrics from.")
+	textFileDirectory = flag.String("collector.textfile.directory", "", "Directory to read text files with metrics from.")
 )
 
 type textFileCollector struct {