This provides data from a specific dataset in various feed formats.
ex: http://trendrr.com/api/feeds/dataset?id=499156&return=xml

authentication is optional (will allow you to view datasets that are not public).

params:

id (required)	this is the id of the dataset
return	This value specifies what format you would like for the feed Possible Values: xml (Default) an xml feed json returns the feed in JSON format excel returns an excel file
start	index of datapoint to start with. a start of 0 would be the oldest datapoint in the dataset.
max	maximum number of datapoints to return.
sort_dir	What direction the datapoints are sorted. Timeseries datapoints are always sorted by date. Possible Values: asc (Default) points are returned oldest first desc points are returned oldest first
start_date	You can specify a start and end date to return only the datapoints between those to dates. Should be in either XML encoding, or the number of seconds since epoch.
end_date	see start_date