Better privacy through local hosting of JS and fonts

[poempelfox]

This PR makes it convenient to host the Javascript and Fonts used by the default templates locally, so there is no need to use external third-party CDNs that can (and will) track your users.
It consists of

• a script (contrib/localjs/fetchfiles.sh) that will download files into a local directory tree, that can then be served by your webserver (or some 'static.domain.tld' if you have such a thing).
• a new config option 'LocalJSPath' that will insert this path to the locally hosted files in the right places in the templates.

As long as LocalJSPath is not set, the templates will behave as before, loading stuff from Google/cloudflare/bootstrapcdn, because of course, this makes initial setup easier for new users. There are however two unavoidable changes to before in that case, in order to keep consistency between locally hosted and not-locally hosted:

• Google Charts API has been replaced with another library, Flot Pie. The reason for this is that Google does not permit to host its charts "API" JS locally, the licensing terms require you to subject your users to Googles invasive tracking.
• font-awesome had to be updated from V4.1.0 to 4.7.0 because 4.1.0 is no longer available for download.

[infertux]

Nice PR. However I wonder whether this project is still being maintained seeing the last commit was 9 months ago? @etix

[etix]

I'll allocate some time next week to review this and maybe plan a new release.

[etix]

Thanks for your great contribution!

Few remarks:

1. It seems there is a JS error if mirrordistchartdata is empty, this occurs if the user IP address does not match any location (your can try this by adding a query argument <somefile>?mirrorlist&fromip=127.0.0.1). Anyway I fixed it by adding a single point representing 100% if no data are returned from the backend.
2. Some commits could have been squashed but that's a minor issue.

Beside that seems good.