Changes to fix IE 11 compatibility

[Bluesmile82]

The following changes were needed to fix IE compatibility:

• Include fetch polyfill: https://github.com/whatwg/fetch
• Use babel-polyfill in every entry in webpack as the first element of an array
• Query string version lowered to 5.0.0 (version 6 is only for modern browsers)

[j8seangel]

I have tried a new library to do the same in Half-Earth and seems to work better: https://github.com/ljharb/qs as it also supports nested properties parsing. So I think worth it to update it here.

[Bluesmile82]

Thanks for the tip. Ready again!