Added support for Marker With Label library

[steveo7]

Added support for the markerWIthLabel library from Google Maps Utility Library V3. See this link for a reference. http://google-maps-utility-library-v3.googlecode.com/svn/tags/markerwithlabel/1.1.8/docs/reference.html

example: http://google-maps-utility-library-v3.googlecode.com/svn/tags/markerwithlabel/1.1.8/examples/basic.html

I added access to labelContent and labelClass marker properties to set from controller code like so;

@json = User.all.to_gmaps4rails do |user, marker|
  marker.title("My title")
  marker.labelContent("My label content")
  marker.json({labelClass: "user_marker_labels"})
end

In your view, turn on by adding :marker_with_label to your marker options then you can add other markerWithLabel properties using the raw option like so;

gmaps(map_options: {...}, markers: {data: @json, options: { marker_with_label: true, ...},
        raw: '{labelStyle: {opacity: 0.75}, labelAnchor: new google.maps.Point(22, 0)}'}})    

[steveo7]

I'll do some refactoring as soon as I can. Thanks for considering this pull request!

[steveo7]

Okay Ben, I removed the two unnecessary edits and made marker with label conditional with a :marker_with_label marker option. Let me know if you think it needs more work. Chao!

[apneadiving]

Sorry guys I've completely changed the gem in v2.

Your code isnt lost though, you'll see you can inject your own builders to adapt to what you really need

Thanks