Add test endpoint to show new NLDI Raindrop Trace endpoint

[kjacobsen16]

Hey everyone, here's some info about our API for calculating the 'raindroppath' (flowline from any lat, lng in CONUS to the nearest NHD flowline) and 'downstreamFlowline' (the down stream section of the NHD Flowline split at the intersection point). Here is the API endpoint: https://nhgf.wim.usgs.gov/processes/nldi-flowtrace/jobs?response=document

Input should look like this:

{
"inputs": [
{
"id": "lat",
"type": "text/plain",
"value": "45"
},
{
"id": "lng",
"type": "text/plain",
"value": "-93"
},
{
"id": "raindroptrace",
"type": "text/plain",
"value": "True"
},
{
"id": "direction",
"type": "text/plain",
"value": "down"
}
]
}

'raindroptrace' can be set to 'true' or 'false' and 'direction' can be set to 'up', 'down' or 'none'. Up will return the upstream portion of the NHD Flowline, down will return the downstream portion and none will return the entirety. Note that the NHD Flowline segment that gets returned includes some stream info in the 'properties' section of the geojson.