Error: Building .msi installers fails when exe has dash (-) in the name

Hello,

I ran into an issue, which I believe should at least be better documented, if not somehow worked around.

Building an MSI installer fails of the project name (as defined in the `package.json` file, I believe) has a dash in the name. For example, my-project.exe fails, and MyProject.exe succeeds.

I believe this is because of the parameter value used in the `template.wxs` file, particularly the injection into the version attribute in the product tag. The error was as follows:

```
Output was:
Setup.wxs
C:\Users\Testing\Documents\my-project\installer\Setup.wxs(2) : error CNDL0108 : The Product/@Version attribute's value, '!(bind.FileVersion.my-project.exe)', is not a valid version. Legal version values should look like 'x.x.x.x' where x is an integer from 0 to 65534.
C:\Users\Testing\Documents\my-project\installer\Setup.wxs(2) : error CNDL0010 : The Product/@Version attribute was not found; it is required.
at Squirrel.Update.Program.d__21.MoveNext()<---

at ChildProcess.proc.on.code (C:\Users\Testing\Documents\my-project\node_modules\electron-winstaller\lib\spawn-promise.js:62:16)
at emitTwo (events.js:106:13)
at ChildProcess.emit (events.js:191:7)
at maybeClose (internal/child_process.js:886:16)
at Process.ChildProcess._handle.onexit (internal/child_process.js:226:5)
```

This is probably because in the `template.wxs` file, the injection into the version looks like `Version="!(bind.FileVersion.{{Id}}.exe)"`, and having a dash in the Id creates a dash in the variable definition, breaking it.

I would suggest either building a workaround (I admit to knowing nothing about these wxs files), or at least, documenting this behavior somewhere.

Thanks!