NcwmsServerTests assert arguments in correct order (ie. expected, actual)
getStyles always returns a map

Change the server-side API for ncWMS layers. We can save a bunch of checking code by changing getStyles() to always return a map. The client-side code will fail if the required information is missing, but the old code would have failed, too, and there is a catch block handling these failures (in JS).
Use real names for styles test
Load default style into drop-down menu

We now read the default palette form the GetMetadata request.
We use roughly the same logic that ncWMS uses to decide what the default style name is.
Sort styles by palette first

In talking to GG about this issue he pointed out that the first thing to do when looking at a dataset is find an appropriate palette. When you have that you can try the arrow styles till you get one that suits. So he asked that the stlyes dropdown is sorted so that styles of the same palette are grouped together.
Merge pull request #1489 from aodn/Issue_#305

Issue #305