Remoteable interface support against 3rd party REST interfaces

Goals:

• Simplify how remoteable interface proxies are exposed in the server and used in the clients.
• Allow interface proxies to be defined against 3rd-party REST interfaces.
• Allow interface proxies to pass Java method parameters as GET parameters.

New annotations:

• @Remotable
  Annotation applied to interface proxy classes. 
   
• path(String), optional
  The absolute or relative path to the REST service.
  When relative path is specified, it's relative to the root-url defined on the RestClient.
  When no path is specified, it's assumed to be the class name ("org.foo.MyInterface")
  
  
• expose(String), optional
  Defines the methods on the interface that are visible.
  Possible values:
  • "ALL" (default) - All methods defined on the interface are visible.
  • "REMOTE" - Only methods marked with the @RemoteMethod annotation are visible.
    
    
• @RemoteMethod
  Annotation applied to Java methods on interface proxy classes. 
  
  
  • path(String), optional
    The path to the REST service for this Java method.
    The default value is the Java method signature (e.g. "myMethod(int,boolean,java.lang.String)").
    
    
  • httpMethod(String), optional
    Defines whether to use GET or POST for the method call.
    Possible values:
    • "POST" (default) - Parameters are serialized using the serializer registered with the RestClient.
    • "GET" - Parameters are serialized using the UrlEncodingSerializer registered with the RestClient.
      
      
• @Query("name")
  Annotation applied to Java method arguments to denote that they are QUERY parameters on the request.

• @FormData("name")
  Annotation applied to Java method arguments to denote that they are FORM post parameters on the request.
  
  
• @Body
  Annotation applied to Java method arguments to denote that they are the HTTP body of the request. 
  
  
• @Header("name")
  Annotation applied to Java method arguments to denote that they are serialized as an HTTP header value. 

Example:

// *** Server side ***

@Remoteable(url="/myremoteable")
public interface MyRemoteableInterface {

   @RemoteMethod(httpMethod="GET", path="/method1")
   public Foo callMyMethod(@Query("count") int count, @Header("E-Tag") String eTag, @Body Bean myBean);
}

// *** Client side ***

RestClient client = RestClientBuilder().rootUrl("http://hostname").build();
MyRemoteableInterface i = client.getRemoteableProxy(MyRemoteInterface.class);
Foo f = i.callMyMethod(123,"foo",new Bean()); 

Other changes:

• Move @Remoteable annotation to a new package:  org.apache.juneau.remoteable.
  All new annotations shown above would be grouped in this package.