Standardized replaceable instead of is_replaceable in json

doc/API.v0.md

@@ -321,7 +321,7 @@ When cyphernode receives a transaction confirmation (/conf endpoint) on a watche
   "size":371,
   "vsize":166,
   "fees":0.00002992,
-  "is_replaceable":0,
+  "replaceable":false,
   "blockhash":"",
   "blocktime":"",
   "blockheight":""
@@ -340,7 +340,7 @@ When cyphernode receives a transaction confirmation (/conf endpoint) on a watche
   "size":371,
   "vsize":166,
   "fees":0.00002992,
-  "is_replaceable":0,
+  "replaceable":false,
   "blockhash":"00000000000000000011bb83bb9bed0f6e131d0d0c903ec3a063e00b3aa00bf6",
   "blocktime":"2018-10-18T16:58:49+0000",
   "blockheight":""

doc/openapi/v0/cyphernode-callbacks.yaml

@@ -116,7 +116,7 @@ components:
           type: "integer"
         fees:
           type: "number"
-        is_replaceable:
+        replaceable:
           type: "integer"
         blockhash:
           $ref: '#/components/schemas/TypeHashString'

proxy_docker/app/script/callbacks_job.sh

@@ -230,7 +230,7 @@ build_callback() {
   if [ -n "${fee}" ]; then
     data="${data}\"fees\":${fee},"
   fi
-  data="${data}\"is_replaceable\":${is_replaceable},"
+  data="${data}\"replaceable\":${is_replaceable},"
   if [ -n "${blocktime}" ]; then
     data="${data}\"blockhash\":\"${blockhash}\","
     data="${data}\"blocktime\":\"$(date -Is -d @${blocktime})\","