= http: Refactor internal Uri implementation class construction.
! util: Swap Duration.Undefined by Duration.Inf, fixes #440

When confugarion is read using the pimped getDuration method the
mapping for "infinite" was Duration.Undefined, but Duration.Undefined !=
Duration.Undefined, which makes comparing any internal settings representation
containing a Duration in a sure failure. Duration.Inf make a lot more sense.
! can: introduce dedicated exceptions for connection failure and request timeout for host-level API
Merge pull request #445 from Net-A-Porter/master

! can: introduce dedicated exceptions for connection failure and request timeout for host-level API
= util: add small and simple cache for creating settings from an ActorSystem
! util: remove SprayActorLogging and UtilSettings, simplify LoggingContext, fixes #421

Since not all SLF4J implementations (most importantly logback) can properly manage a potentially unbounded number of loggers we cannot use actor paths as logger names. The latter would have been nice since, by converting actor paths to dotted notation, we'd be able to use hierarchical configuration as well as logbacks abbreviation feature. However, since we can't use actor paths as logger names the feature of "dottifying" actor paths is not useful.

The `SprayActorLogging` and `UtilSettings` abstractions therefore don't serve any purpose anymore.
Please replace all your usage of `spray.util.SprayActorLogging` with `akka.actor.ActorLogging`, which provides the exact same API.
= routing: small fix in tests, closes #453
Merge pull request #441 from ivantopo/issues/440

! util: Swap Duration.Undefined by Duration.Inf, fixes #440
Merge pull request #416 from asnare/uri-impl-refactor

Refactor internal Uri implementation class construction.
Merge pull request #452 from spray/ticket/421

Fix #421: SprayActorLogging and LoggingContext creating memory leak
+ http: support proxy authentication
= sbt: change spray-testkit dependency on akka-testkit from 'provided' to 'compile'
= utils: remove unnecessary synchronisation on SettingsCompanion
Merge pull request #447 from mighdoll/lee/akka-testkit-dependency

fix #446: spray-testkit has a 'runtime' dependency on akka-testkit
= http: refactor auth headers
- move Challenge to AdditionalRules
- move Www-/Proxy-Authenticate to SimpleHeaders
- move Proxy-Authorization to AuthorizationHeader
- delete ProxyAuthenticateHeader, ProxyAuthorizationHeader, WwwAuthenticateHeader
Merge pull request #451 from 2beaucoup/feature/proxy-auth

+ http: support proxy authentication
Merge pull request #425 from jrudolph/wip/chunkless-request-streaming

+ can: add `spray.can.client/server.incoming-auto-chunking-threshold-size`, fixes #189
! can: make Content-Length a long value, fixes #443

API changes:
  * `max-content-length` setting is now also a Long
  * `incoming-auto-chunking-threshold-size` is now also a Long

This change makes only sense in combination with (auto-)chunking,
because we are not able to support byte arrays bigger than Int.MaxValue.