Get points from websockets after initial load

[oscgonfer]

So, as commented in fablabbcn/smartcitizen-api#197, we should consider having this approach for the data

in index view

1. load world map at the beginning
2. subscribe to websockets to append changes on devices post, same as now.smartcitizen.me approach

in graph view

1. load the data based on settings.js with a predefined time-span (delta days)
2. add a reload button and a calendar picker in the plots view to reload data
3. subscribe to the websockets endpoint to append data to corresponding id, only in plot view

Do you agree?