support v4 signature method and json style request protocol

[umegaya]

to support kinesis. basic API usage, please see test/kinesis.lua

caveat

some of api described in here, not supported because aws-sdk-js v1.x repo's service definition does not describe them. in aws-sdk-js v2.x, service definition have big change, so I only borrow them from v1.x's. but basic operation (create/delete/list/describe/put/get) are supported.

caution

• this version will break backward compatibility for return value of api call
  • because with current api spec, it is hard to know api call is success or not when api level error occurs.
  • but if lua level error occurs, it returns false and lua-error object. it is highly inconsistent and should be fixed.

local api = AWS.EC2:api()
-- new api call : returns {status, data or api_level_error or lua_level_error}
ok, r = api:describeInstances()
-- old api call : returns { data or api_level_error or false, lua_level_error(if occurs) }
r, lua_err = api:describeInstances()

• after this version merged, api call returns 2 values which represents status and (response data/api level error/lua level error).
• add oldReturnValue = true to initial AWS config, you can get previous style return value.

local AWS = require ('lua-aws.init')
AWS = AWS.new({
    accessKeyId = os.getenv('AWS_ACCESS_KEY'),
    secretAccessKey = os.getenv('AWS_SECRET_KEY'),
    oldReturnValue = true,
})