[bitshares/bitshares-core] unsigned_int unpacking (#1267)

«`
[ 93%] Building CXX object libraries/plugins/elasticsearch/CMakeFiles/graphene_elasticsearch.dir/elasticsearch_plugin.o

Broadcast message from root@travis-job-2cd07e9d-7fb4-490c-8b3e-31a13c875a31
(unknown) at 22:14 …
The system is going down for power off NOW!
[ 94%] Linking CXX static library libgraphene_witness.a
«`
Restarted.