[SETUP] Pin the gems to Vagrant 1.0.6 and Berkshelf 1.2.1

Also added by @dmichael as dmichael/cookbook-elasticsearch@8c5af3f.

Closes #92
[VAGRANT] Remove the dependency on "active_support"

Remove loading ActiveSupport's Hash#deep_merge and copy&paste it directly into Vagrantfile,
in preparation to for supporting Vagrant > 1.1
Update Elasticsearch version to 0.20.6

Closes #81
Pin the "fog" gem to version 1.10.1 to prevent "Unable to activate" errors

    FATAL: Gem::LoadError: ruby_block[Create EBS volume on /dev/sda2 (size: 25GB)] (elasticsearch::ebs line 16) had an error: Gem::LoadError: Unable to activate fog-1.11.1, because json-1.5.4 conflicts with json (~> 1.7)

Closes #93
Use `node.elasticsearch.network.host` and `node.elasticsearch.http.port` in Nginx proxy configuration (if set)

Implemented by abusing Ruby's `rescue` clause, for the sake of not doing some
`if  node.elasticsearch &&  node.elasticsearch.network &&  node.elasticsearch.network.host`
insanity required by (incorrect!) Chef approach for handling missing attributes.

Because `node.not.really.there` _should_ return `nil`, not fail with an exception.

Closes #85