Major changes

renamed the group id from com.softwaremill.sttp to com.softwaremill.sttp.client (organization)
renamed the main package from com.softwaremill.sttp to sttp.client (see #288)
renamed initial request from sttp to basicRequest
reworked response-as (see #284)
- asString now is an Either[String, String] not a String (no assumptions as to the error type)
- all json integrations return an Either[ResponseError, B] body
added websocket support

Minor changes

removed Request.parseResponseIf
removed Response.unsafeBody
redirect loops now throw an exception
reduce import conflicts with cats:
- rename Id to Identity (to make working w/ cats easier)
- move MonadError to another package
cats, zio, monix, scalaz backends now return results wrapped in IO/Task when creating a backend
backend.close returns a F[Unit] - watch out if you are using lazy wrappers!
StatusCode is a proper type
Header is a proper type
Multipart renamed to Part and generified
asFile(overwrite) - removed the overwire parameter
QueryFragment(Encoding) in Uri renamed to QuerySegment(Encoding)
Uri.parse, Uri.apply removed, replaced with safeApply
uri"..." without scheme throws exception
SttpBackendStub: instantiated using .stub on "real" backend companion object, instead of using an instance of the "real" backend