Update to Geocoder v3 and register named providers

[ilyashtrikul]

• According to

Major version 2 will reach end of life on December 2015

needs to update Geocoder version in composer.json.

• We can configure only chain provider. With my fix we can register named providers (and chain too), and call them with Geocoder::using('provider_name').

[toin0u]

@shtricul Thank you. It looks good. Can you update the doc as well please? :)

[dccampbell]

So...has this change been held back for over a half year just for documentation? If it's fully functional, any chance of getting it merged in? Or maybe start a release branch to pull in other updates as well and encourage doc updates before merging to master and tagging a release? cc @toin0u @shtricul

[mikebronner]

Thanks for this PR ... we are implememting an update to Geocoder v3.3.x and should have it out shortly. Closing this PR for now, as things have changed somewhat and we have another similar PR in the works. Thanks for your efforts though, please continue submitting PRs if you see something.