Minor: Convert single quote strings to double quote ones in the templates

[empz]

Following your own Typescript coding standards strings should be double quoted.

Opening a template project with VSCode with TSLint or any other editor with TSLint will underline every string present in the .tsx files as they are all single quoted.

[SteveSandersonMS]

Pull requests welcome!

[stephtr]

#360
I hope it is okay to also convert quotes in webpack.config.* files for consistency.

[SteveSandersonMS]

After further consideration, and with reasons outlined here, we're going to stick with ' in the default templates for now. Obviously you can change it to whatever you want in your own projects!