remove FAIL_SUBSCRIBE action

src/actions/constants/blockchain.js

@@ -1,6 +1,5 @@
 /* @flow */
 
 export const START_SUBSCRIBE: 'blockchain__start_subscribe' = 'blockchain__start_subscribe';
-export const FAIL_SUBSCRIBE: 'blockchain__fail_subscribe' = 'blockchain__fail_subscribe';
 export const READY: 'blockchain__ready' = 'blockchain__ready';
 export const UPDATE_FEE: 'blockchain__update_fee' = 'blockchain__update_fee';