MAJOR: stick-tables: use sample types in place of dedicated types

This patch is the first step for sample integration. Actually
the stick tables uses her own data type, and some converters
must be called to convert sample type to stick-tables types.

This patch removes the stick-table types and replace it by
the sample types. This prevent:
 - Maintenance of two types of converters
 - reduce the code using the samples converters
diff --git a/include/types/stick_table.h b/include/types/stick_table.h
index 373ded4..d48905f 100644
--- a/include/types/stick_table.h
+++ b/include/types/stick_table.h
@@ -31,6 +31,7 @@
 #include <eb32tree.h>
 #include <common/memory.h>
 #include <types/freq_ctr.h>
+#include <types/sample.h>
 
 /* stick table key types */
 enum {
@@ -180,19 +181,11 @@
 
 extern struct stktable_data_type stktable_data_types[STKTABLE_DATA_TYPES];
 
-/* stick table key data */
-union stktable_key_data {
-	struct in_addr ip;        /* used to store an ipv4 key */
-	struct in6_addr ipv6;     /* used to store an ipv6 key */
-	uint32_t integer;         /* used to store an integer key */
-	char buf[0];              /* dynamically allocated, used to store a null terminated string key or a buffer of data */
-};
-
 /* stick table key */
 struct stktable_key {
 	void *key;                      /* pointer on key buffer */
 	size_t key_len;                 /* data len to read in buff in case of null terminated string */
-	union stktable_key_data data;   /* data, must always be last */
+	union sample_value data;
 };
 
 /* WARNING: if new fields are added, they must be initialized in stream_accept()