Leaflet detection not enough restrictive

[ArnaudLigny]

For example on https://contacts.google.com/preview/all it detects the Leaflet library with an undefined version.
I think it's because the name is too short: "L".

I suggest we could force control of "version" property to be sure it's really the Leaflet lib:

'Leaflet': {
        icon: 'leaflet',
        url: 'http://leafletjs.com',
        test: function(win) {
            if (win.L && win.L.version) {
                return {version: win.L.version};
            }
            return false;
        }
    },

[johnmichel]

@Narno, good catch!

This is something I've been meaning to go through as a part of #15. Some of the library detection tests need to be hardened to handle situations like this. It's been done for a handful of libraries, as seen here, but more is definitely necessary. This will be addressed soon.

[ArnaudLigny]

@johnmichel, I can help with a PR of the code above if you want?