Added interface for ParseFilter and ParseFilters utility
Improved ParseFilter + generate DOM in ParserBolt if necessary + simple example to use XPATH (work in progress)
PrinterBolt displays K/V when finding a Map
examples of working parsefilters
BugFix KeyValues
Renamed DebugMetricConsumer -> DebugMetricsConsumer + removed unused package declarations + javadoc description
distinguish missing URL field from empty value for the field
RandomURLSpout now has a constructor to pass the list of URLs to randomly emit from