Fix promu build

.promu.yml

@@ -1,6 +1,8 @@
 repository:
     path: github.com/martinlindhe/wmi_exporter
 build:
+    binaries:
+        - name: wmi_exporter
     ldflags: |
         -X {{repoPath}}/vendor/github.com/prometheus/common/version.Version={{.Version}}
         -X {{repoPath}}/vendor/github.com/prometheus/common/version.Revision={{.Revision}}

Makefile

@@ -2,4 +2,4 @@ fmt:
 	gofmt -l -w -s .
 
 build:
-	promu build -v .
+	promu build -v

appveyor.yml

@@ -22,7 +22,7 @@ install:
 build_script:
   - ps: gitversion /output json /showvariable FullSemVer | Set-Content VERSION -PassThru
   - govendor test -v +local
-  - promu build -v .
+  - promu build -v
   - ps: |
       $ErrorActionPreference = "Stop"
       if($env:APPVEYOR_REPO_TAG -eq "True") {