* Added Clixon Restconf library

* Builds and installs a new restconf library: libclixon_restconf.so and clixon_restconf.h
  * The restconf library can be included by a restconf plugin.
  * Example code in example/Makefile.in and example/restconf_lib.c
* Authorization
  * Example extended with authorization
  * Test added with http basic authorization (test/test_auth.sh)
  * Documentation in FAQ.md
* README.md extended with new yang, netconf, restconf, datastore, and auth sections.

example/example.yang

@@ -11,4 +11,21 @@ module example {
     }
     description
 	"Example code that includes ietf-ip and ietf-routing";
+    leaf basic_auth{
+	description "Basic user / password authentication as in HTTP basic auth";
+	type boolean;
+	default false;
+    }
+    list auth {
+	description "user / password entries. Valid if basic_auth=true";
+	key user;
+	leaf user{
+	    description "User name";
+	    type string;
+	}
+	leaf password{
+	    description "Password";
+	    type string;
+	}
+    }
 }