Added missing pkg/errors dependency

glide.lock

@@ -29,6 +29,8 @@ imports:
   version: 5411d3eea5978e6cdc258b30de592b60df6aba96
 - name: github.com/mattn/go-isatty
   version: 281032e84ae07510239465db46bf442aa44b953a
+- name: github.com/pkg/errors
+  version: 248dadf4e9068a0b3e79f02ed0a610d935de5302
 - name: github.com/spf13/pflag
   version: 9ff6c6923cfffbcd502984b8e0c80539a94968b7
 - name: github.com/syndtr/goleveldb

glide.yaml

@@ -34,6 +34,8 @@ import:
   - proto
 - package: github.com/gorilla/websocket
 - package: github.com/spf13/pflag
+- package: github.com/pkg/errors
+  version: ^0.8.0
 - package: golang.org/x/crypto
   subpackages:
   - ripemd160