[BUG/CLEANUP] cookiedomain -> cookie_domain rename + free(p->cookie_domain)

Rename cookiedomain -> cookie_domain to be consistent with current
naming scheme. Also make sure cookie_domain is deallocated at deinit()
diff --git a/include/types/proxy.h b/include/types/proxy.h
index 81e182d..9129861 100644
--- a/include/types/proxy.h
+++ b/include/types/proxy.h
@@ -161,7 +161,7 @@
 		void (*server_drop_conn)(struct server *);/* to be called when connection is dropped */
 	} lbprm;				/* LB parameters for all algorithms */
 
-	char *cookiedomain;			/* domain used to insert the cookie */
+	char *cookie_domain;			/* domain used to insert the cookie */
 	char *cookie_name;			/* name of the cookie to look for */
 	int  cookie_len;			/* strlen(cookie_name), computed only once */
 	char *url_param_name;			/* name of the URL parameter used for hashing */