Enhancement: Support Option Templates/Data

[nickbroon]

Just recording here for others that bump into this.
Vermont does not support forwarding/sending Ipfix Option templates/data. These are widely used for things like metering process statistics, information on interfaces, sampling, flow keys. See https://tools.ietf.org/html/rfc7011#section-4

https://github.com/tumi8/vermont/blob/master/src/modules/ipfix/IpfixSender.cpp#L257
https://github.com/tumi8/vermont/blob/master/src/modules/ipfix/IpfixSender.cpp#L536

are the key places support needs added.