Mobile UI improvemnts for the "graph" page

This branch contains mobile improvements for the "graph" view. This is a fix for issue #58.

If the viewport is smaller than 768px the following changes are made to the UI:
* the "Pacman" button is removed
* the search-input is removed
* the refresh-time-label is removed
* the settings-panel is hidden by default
* the reload button gets replaces by an icon-button
* the color-changer button gets replaces by an icon-button

This pull-request also includes the following improvements:
* a new settings button gets added to the right of the header-bar. This button is a addition to the existing "toggle" button.
* a simple static-nodejs-webserver-script "server.js" was added for developing purposes
* a simple index.html file was added with a link to the different sup-pages
* "stats" was removed (I think it was not working anymore!?)

[There is also an demo-version live](mojoaxel.github.io/ffmap-d3/).