Fixes #72 #76 #77 - Created game template and updated base templates

Added css for fixed navbar and fixed footer.
Added jquery.svg package for drawing games graphics.
The game and associated files are served using the gameflownode URL.

GAME TEMPLATE
The game-template extends base.html and opens new blocks: gamehead
and gameblock, for adding head scripts and the game content.

Created modal frame for presenting games.
Added loading function waiting for resources to load that is executed
automatically when inheriting from game_base template.

Game template includes the ".games" variable with standar functions
of games. Still not including logging functions.
When game is started, function game_start must be called,
and so .games variable to count seconds played is automatically updated.