Fix resources path to launch CLI on Windows

Hello there. I had to use Windows from time to time, and found out WakaTime PyCharm plugin
didn't work there, silently failing. Everything looked okay, but data was never reported to a server.

I found out that resources location had a slash prepended (i.e. `/C:/Foo/…`) which resulted in silent inability to launch CLI (`pythonw /C:/…` didn't found the script).

This patch fixes it for me.