Remove unused import.

Author: rlubke

providers/grizzly/src/main/java/org/asynchttpclient/providers/grizzly/statushandler/ProxyAuthorizationHandler.java

@@ -23,7 +23,6 @@
 import org.asynchttpclient.util.Base64;
 import org.glassfish.grizzly.Connection;
 import org.glassfish.grizzly.filterchain.FilterChainContext;
-import org.glassfish.grizzly.http.HttpContext;
 import org.glassfish.grizzly.http.HttpResponsePacket;
 import org.glassfish.grizzly.http.Method;
 import org.glassfish.grizzly.http.util.Header;