new 'styles' options for Polyline styling
make trailer opacity configurable with styles option
hide trailer initially, show on click/move when hidden
 (enable has no mouse position)
add styling example
Added Gitter badge
Merge pull request #31 from gitter-badger/gitter-badge

Add a Gitter chat badge to README.md
Merge pull request #30 from nrenner/styles

Polyline styling options
Add GitHub ribbon to OSM example