* refactored `process.HttpRaw` and `process.HttpDapr` into a single e…

…ntity `process.Http`

* introduced `transform` package with `TransformationFunc` type to implement transformation functions for messages data
* added first `TransformationFunc` implementation `DaprAws` for Dapr messages transformation when running with AWS SNS/SQS driver
* the `Run` function of `process.Processor` interface now accepts `transform.TransformationFunc` as third parameter
* configuration parser now supports new config section `transformer`
* updated documentation and example configuration files in `examples` directory

* moved packages from `internal` directory to the root

* added `http_dapr` `Processor` implementation
* using context with AWS API calls
* moved configuration parsing to `getPollLaunchConfig` function
* moved example scripts and configuration files to `examples` directory
* updated README.md