change `process.versions.electron` to reflect suffixes in version name.

npm/install.js

@@ -1,7 +1,6 @@
 #!/usr/bin/env node
 
-// maintainer note - x.y.z-ab version in package.json -> x.y.z
-var version = require('./package').version.replace(/-.*/, '')
+var version = require('./package').version
 
 var fs = require('fs')
 var os = require('os')