Removing special character from metric and label name

[dinumathai]

If I have a "-' in my kafka topic name the metrics exported by the exporter is failing at promethues during scraping.

Need changes in "KafkaCollector.java"
String metricName = topic.replaceAll("[^A-Za-z0-9]","") + "" + record.getName().replaceAll("[^A-Za-z0-9]","");
labelNames.add(entry.getKey().replaceAll("[^A-Za-z0-9]",""));

[dinumathai]

Fixed this issue and Dockerized the exporter - dinumathai/kafka-topic-exporter