Migrated the Memory layer to the Platform layer

Deprecated POLARSSL_MEMORY_C and placed placeholder for memory.h to make
sure current code will not break on new version.
diff --git a/library/Makefile b/library/Makefile
index 9316024..a4a3ce7 100644
--- a/library/Makefile
+++ b/library/Makefile
@@ -46,7 +46,7 @@
 		error.o		gcm.o		havege.o		\
 		hmac_drbg.o								\
 		md.o		md_wrap.o	md2.o			\
-		md4.o		md5.o		memory.o		\
+		md4.o		md5.o						\
 		memory_buffer_alloc.o	net.o			\
 		oid.o									\
 		padlock.o	pbkdf2.o	pem.o			\