Adding of Leaflet map using basic tutorial from their site
* Map point to Poznan for this time
* Map fill almost all window of browser
* Adding of url for API-based GeoJSON of issues' geometries
* Adding dummy view for API-based GeoJSON of issues' geometries
* Adding static (for now) template for GeoJSON of issues' geometries
* Some typos in dummy geojson
* Adding of layer for geojson, getting data using jquerry ajax method