Style change

In this pull request changed around some of the HTML to reduce the number of containers, make the navbars fixed position so the main bootstrap container with the grid and desktop views took up the rest of the space.

I also address issues:
#90 - Maximize widget: this needed the html to be modified so the widget could take 100% of the main window container
#56 toggle themes: a light and a dark theme are now enabled, tied to the settings modal. dark theme came from the mockups as much as possible, light theme is not.
#87 re-apply css: application of css partially done - primarily taken from mockup though
I don't really see the point of removing this, since that space isn't usable by anything else at this point (now that the search bar is gone). I'd vote to leave it in until there's something better to take its place.