Rename references of HTTPClientConfiguration to HTTPClient.Configuration (#19)

Author: Trevör

README.md

@@ -92,15 +92,15 @@ httpClient.execute(request: request).whenComplete { result in
 Enable follow-redirects behavior using the client configuration:
 ```swift
 let httpClient = HTTPClient(eventLoopGroupProvider: .createNew,
-                            configuration: HTTPClientConfiguration(followRedirects: true))
+                            configuration: HTTPClient.Configuration(followRedirects: true))
 ```
 
 ### Timeouts
 Timeouts (connect and read) can also be set using the client configuration:
 ```swift
 let timeout = Timeout(connectTimeout: .seconds(1), readTimeout: .seconds(1))
 let httpClient = HTTPClient(eventLoopGroupProvider: .createNew,
-                            configuration: HTTPClientConfiguration(timeout: timeout))
+                            configuration: HTTPClient.Configuration(timeout: timeout))
 ```
 or on per-request basis:
 ```swift

Sources/NIOHTTPClient/HTTPClientProxyHandler.swift

@@ -17,7 +17,7 @@ import NIOHTTP1
 
 /// Specifies the remote address of an HTTP proxy.
 ///
-/// Adding an `HTTPClientProxy` to your client's `HTTPClientConfiguration`
+/// Adding an `HTTPClientProxy` to your client's `HTTPClient.Configuration`
 /// will cause requests to be passed through the specified proxy using the
 /// HTTP `CONNECT` method.
 ///