Change Cpu.Get() on Windows to not use floating point artimetic

CHANGELOG.asciidoc

@@ -51,6 +51,7 @@ https://github.com/elastic/beats/compare/v1.1.0...master[Check the HEAD diff]
 - Check column length in pgsql parser. {issue}565{565
 
 *Topbeat*
+- Fix issue with cpu.system_p being abnormally high {pull}1200[1200]
 
 *Filebeat*
 - Stop filebeat if filebeat is started without any prospectors defined or empty prospectors {pull}644[644] {pull}647[647]

topbeat/beater/topbeat.go

@@ -436,9 +436,9 @@ func (t *Topbeat) addCpuPercentage(t2 *CpuTimes) {
 		calculate := func(field2 uint64, field1 uint64) float64 {
 
 			perc := 0.0
-			delta := field2 - field1
+			delta := int64(field2 - field1)
 			perc = float64(delta) / float64(all_delta)
-			return Round(perc, .5, 2)
+			return Round(perc, .5, 4)
 		}
 
 		t2.UserPercent = calculate(t2.Cpu.User, t1.Cpu.User)
@@ -460,7 +460,7 @@ func (t *Topbeat) addCpuPercentageList(t2 []CpuTimes) {
 			perc := 0.0
 			delta := field2 - field1
 			perc = float64(delta) / float64(all_delta)
-			return Round(perc, .5, 2)
+			return Round(perc, .5, 4)
 		}
 
 		for i := 0; i < len(t1); i++ {

topbeat/beater/topbeat_test.go

@@ -104,8 +104,8 @@ func TestCpuPercentage(t *testing.T) {
 
 	beat.addCpuPercentage(&cpu2)
 
-	assert.Equal(t, cpu2.UserPercent, 0.95)
-	assert.Equal(t, cpu2.SystemPercent, 0.04)
+	assert.Equal(t, cpu2.UserPercent, 0.9502)
+	assert.Equal(t, cpu2.SystemPercent, 0.0448)
 }
 
 func TestProcMemPercentage(t *testing.T) {