Feature/mongodb conditional updates

[amarziali]

Several improvements here:

• MongoDB: Allow to use custom condition for upserts
• MongoDB: Fix potentials data loss (also reported by MongoDB and Solr Service sinks may retain some records under some conditions #409)
• Framework: introduce datatime field type
• Framework: extend the EL to use accessors (e.g. maps and nested types)
• Serializers: Use Avro 1.8.2
• Serializers: Allow ExtendedJsonSerializer to interpret date/time/datetime from an avro schema
• Processors: ExpandMapField processor to flatten map field to the record root
• HDFS: Allow hdfs burner to gather raw data and interpret as a json by joining dataframe with record type and datetime in order to have expected information needed for partitioning partitioning