Implemented server side district validation

If place is not located in related district, error is raised. This implements server side part of issue #23.
Fixed Grunt configuration not to restart development server on server test file change
Added missing semicolon
Added Leaflet directly to container.js

Previously Leaflet.js was loaded from CDN which was causing issues. Now it may take longer to load app but it should be mitigated by planned gzip support.
Added client side district validation

If place has related district then place location has to be inside of the district. If district is not defined, then place has to be in Prague bounding box. Fixes #23.