Handle oracle operation in FATE (#90)

* Handle oracle operation in FATE

Keep oracle type information on fcode level

Introduce typereps as values

Handle oracle registration

Handle oracle query object and oracle_query op

Handle oracle get question

Handle oracle query fee

Handle oracle get answer

Handle oracle respond

Handle oracle extend

* Address review comment

test/aeso_compiler_tests.erl

@@ -118,8 +118,7 @@ compilable_contracts() ->
     ].
 
 not_yet_compilable(fate) ->
-    ["oracles",             %% Oracle.register
-     "events",              %% events
+    ["events",              %% events
      "address_literals",    %% oracle_query_id literals
      "address_chain"        %% Oracle.check_query
     ];