[Bug 420930] Use Charset to specify character encoding

Signed-off-by: Mikhail Mazursky <mikhail.mazursky@gmail.com>
Merge remote-tracking branch 'origin/master' into jetty-9.1

Conflicts:
	jetty-client/src/main/java/org/eclipse/jetty/client/util/DigestAuthentication.java
	jetty-client/src/test/java/org/eclipse/jetty/client/HttpReceiverTest.java
	jetty-client/src/test/java/org/eclipse/jetty/client/HttpSenderTest.java
	jetty-http/src/main/java/org/eclipse/jetty/http/HttpField.java
	jetty-server/src/test/java/org/eclipse/jetty/server/AbstractHttpTest.java
	jetty-servlets/src/test/java/org/eclipse/jetty/servlets/AbstractDoSFilterTest.java
	jetty-spdy/spdy-core/src/main/java/org/eclipse/jetty/spdy/generator/HeadersBlockGenerator.java
	jetty-spdy/spdy-core/src/main/java/org/eclipse/jetty/spdy/parser/HeadersBlockParser.java
	jetty-websocket/websocket-client/src/main/java/org/eclipse/jetty/websocket/client/ClientUpgradeRequest.java
	jetty-websocket/websocket-common/src/main/java/org/eclipse/jetty/websocket/common/WebSocketFrame.java
	jetty-websocket/websocket-common/src/main/java/org/eclipse/jetty/websocket/common/WebSocketSession.java
	jetty-websocket/websocket-common/src/test/java/org/eclipse/jetty/websocket/common/extensions/compress/DeflateCompressionMethodTest.java
	jetty-websocket/websocket-common/src/test/java/org/eclipse/jetty/websocket/common/extensions/compress/PerMessageDeflateExtensionTest.java