Due to developer confusion over nomenclature, the ID was used in lieu of
the Application property of `Layout`. `layout.Application` holds the
user-facing name for a particular layout, and is what should be paired
with a measurement name in the `/mappings` endpoint.
Before
------
```
% curl http://localhost:8888/chronograf/v1/mappings
{
"mappings" : [
{
"name" : "18aed9a7-dc83-406e-a4dc-40d53049541a",
"measurement" : "disk"
}
]
}
```
After
-----
```
% curl http://localhost:8888/chronograf/v1/mappings
{
"mappings" : [
{
"measurement" : "disk",
"name" : "User Facing Application Name"
}
]
}
```
Connect #326
cb37de2d76