Fix import org.apache.http.protocol.HttpContext;

Author: benjchristensen

rxjava-contrib/rxjava-apache-http/src/main/java/rx/apache/http/ObservableHttp.java

@@ -21,7 +21,7 @@
 import org.apache.http.nio.client.HttpAsyncClient;
 import org.apache.http.nio.client.methods.HttpAsyncMethods;
 import org.apache.http.nio.protocol.HttpAsyncRequestProducer;
-import org.apache.http.protocol.Http.HttpContext;
+import org.apache.http.protocol.HttpContext;
 import org.apache.http.protocol.BasicHttpContext;
 
 import rx.Observable;