Consolidate JetBrains IDE tempates into Global/IDEA template

Since all of these IDEs produce the same layout of project files, it seems redundant to have separate templates, especially when they handle the same problem slightly differently. References:

  * This [Knowledge Base article](s://intellij-support.jetbrains.com/entries/23393067-How-to-manage-projects-under-Version-Control-Systems)
  * This [answer](http://stackoverflow.com/a/1031116/759418)
  * This [documentation page](http://www.jetbrains.com/idea/webhelp/project.html)

I'm not entirely sure which files under `.idea/` are user-specific or sensible to ignore even when checking in the rest of that directory, so it would be good if someone with a better idea could confirm if the choices in the new IDEA template are sensible.