Add thread safe method of querying BigCommerce resources.

[pedelman]

Example usage

# Thread safe
conn = Bigcommerce::Connection.build(
  Bigcommerce::Config.new(
    store_hash: ENV['BC_STORE_HASH'], 
    client_id: ENV['BC_CLIENT_ID'], 
    access_token: ENV['BC_ACCESS_TOKEN']
  )
)

Bigcommerce::System.time(connenction: conn)
=> #<Bigcommerce::System time=1466546702>

Bigcommerce::System.raw_request(:get, '/time', connection: conn)
=> #<Faraday::Response:0x007fd4a4063170 ... >>

# Not thread safe
Bigcommerce.configure do |config|
  config.store_hash = ENV['BC_STORE_HASH']
  config.client_id = ENV['BC_CLIENT_ID']
  config.access_token = ENV['BC_ACCESS_TOKEN']
end

Bigcommerce::System.time
=> #<Bigcommerce::System time=1466546702>

Bigcommerce::System.raw_request(:get, '/time')
=> #<Faraday::Response:0x007fd4a4063170 ... >>

Fixes #98

[pedelman]

ping @mattolson @saurabh-g @jason0415 @gregory

[mattolson]

What is this for?

[gregory]

had a quick high level overview but not tested.
Overall looks good!
One thing i'm not really a fan of is tempering with parameters
I do believe that passing connection objects is the way to go to solve thread safety but also have the ability to query multiple stores.

[gregory]

Also, don't you feel like it's kind of a "hack" to allow to pass parameters, just to be able to sneak in the connection object? :)

What i'm saying is that you allow me to do this: Bigcommerce::System.time(foo: 'bar') but this is just so you can pass in a connection: Bigcommerce::System.time(connenction: conn)

[mattolson]

👍