django-chartit charts and pages optimization

[garyyu]

• add django-chartit charts
• a lot of optimization on pages

Note: django-chartit need jquery and highcharts:

npm install highcharts --save
npm install jquery --save

[garyyu]

@ignopeverell Could you assign this repository's Write permissions to @quentinlesceller ? so as he also can merge pull requests when you're busy on Grin repo. thanks~

[hendi]

Thanks for the PR, I'll have a look at it later today :)

[hendi]

Great work with the charts, and also with the design changes! I'll merge it and update grinexplorer.net now :)