Added labels to features in the gpx layer

Hi, I'm new to git so here is my second attempt at the pull request.  Sorry if there are any mistakes in the process.  For a RedCross project I've have been asked to update the gpx renderer to load points and to also label the features.  The changes I made in my previous request were from a dependency.  Turns out that project has already been updated for this, so is it possible to update togeojson.js to the latest version which supports points, routes etc?

With the two files here I've updated the gpx render to show the feature's name next to itself and updated the css appropriately.

Unfortunately I couldn't get the test environment working on my set-up, so couldn't run npm.  Is that going to be a problem?