Upgrade to Jetty 9.4.8.v20171121

 + 212 HttpClient should support pluggable AuthenticationStore
 + 215 Add Conscrypt for native ALPN/TLS/SSL
 + 272 WebSocket hangs in blockingWrite
 + 487 JDK 9 build compatibility
 + 901 Overriding SSL context KeyStoreType requires explicit override of
   TrustStoreType
 + 922 Implements methods Connection.getBytes[In|Out]()
 + 1209 IllegalStateException when HTTP/2 push is disabled
 + 1213 Upgrade to ASM Version 6.0 for JDK9
 + 1509 Improve GZIPContentDecoder buffer pooling sizing
 + 1550 Resolve inconsistent Shutdown configuration with Jetty Runner
 + 1640 Introduce :run-distro goal for local jetty distribution deployment
 + 1692 Annotation scanning should ignore `module-info.class` files
 + 1696 Missing stacktraces on debug of WriteFlusher onFail
 + 1705 Rejected executions in QueuedThreadPool can lead to memory leaks
 + 1760 Update to apache jasper 8.5.20
 + 1768 Allow jetty properties to be set for the jetty:run-forked goal
 + 1782 Using assembly.tarLongFileMode=posix for jetty-home and
   jetty-distribution assembly
 + 1797 JEP 238 - Multi-Release JAR files break bytecode scanning
 + 1806 Improved ReservedThreads idle timeout
 + 1807 Add new HttpChannel listener and events for metrics libraries
 + 1814 Move JavaVersion to jetty-util for future Java 9 support requirements
 + 1818 Improve Infinispan support on JDK 9
 + 1819 Race condition during annotation parsing
 + 1823 ResourceHandler with ranged requests does not return Content-Type
   response header
 + 1829 OSGi webbundle classes scanned twice
 + 1833 Request.startAsync requires context path
 + 1835 Locker is not reentrant on ServerConnector#setConnectionFactories
 + 1836 Migrate Locker implementation to JVM ReentrantLock implementation
 + 1841 Reduce contention on ServletHolder
 + 1845 Allow null User-Agent in HttpClient
 + 1849 Refactoring of SelectorManager.defaultSchedulers()
 + 1851 Improve insufficient thread warnings/errors
 + 1854 Consistent IOException and timeout handling when extracting form
   parameters
 + 1856 ResourceHandler without ServletContext throws NPE for welcome files if
   used directly
 + 1857 GZIPContentTransformer fails to send entire message if used with
   BufferedContentTransformer
 + 1865 Improve Exception on invalid redirect usage
 + 1867 Improve Exception thrown during Expect 100 Continue
 + 1868 Need a way to randomly select ports for tests
 + 1871 JMXify SslContextFactory
 + 1878 Handle 100 Continue response without Expect header
 + 1879 'Bad tld url' seen during :jetty-run when running integration tests
 + 1881 Improve support of WebSocket over Unix Domain Socket
 + 1885 SessionHandler get/set maxInactiveInterval is not symmetric with
   negative values
 + 1888 Implement cookie matching on Path attribute per RFC 6265
 + 1891 Make HTTP/2 async error notifications configurable
 + 1892 NPE resulting from bad JEP 238 MultiReleaseJarFile structure
 + 1893 Add ability to set HttpClient Connection TTL
 + 1897 Introduce a round-robin connection pool for HttpClient
 + 1900 Update to CDI 2.0 for cdi module
 + 1901 Reimplement PathWatcher as scanner
 + 1909 Update to Apache Jasper 8.5.23
 + 1910 Remove unused jetty-jsp module
 + 1912 AbstractConnector EndPoint leak for failed SSL connections
 + 1914 HttpClient fails to parse Content-Type response header with RFC 2045
   charset="utf-8" syntax
 + 1919 Review LowResourceMonitor
 + 1920 Connect Timeouts with NonBlocking CreateEndPoint
 + 1924 ManagedSelector can livelock under high load
 + 1931 Expose RolloverOutputStream for pluggable behaviour
 + 1933 Use CLASSPATH for scanning java9 system classes
 + 1956 Store and report build information of Jetty
 + 1958 Blocking Timeout has different behavior in HttpInput vs HttpOutput
 + 1970 ManagedSelector can lose selector thread under high concurrent load
 + 1980 PushCacheFilter does not push TLS offloaded HTTP/2 requests
 + 1981 Loading resource content failed
 + 1984 Remove jetty-client dependency in jetty-rewrite