Some optimization was made

* I removed javascript from templates to .js files and encapsulated them in module
* Fixed bug on editing event (image did not change)
* changed datetime picker with different one, which prevents input of past date (still needed some optimization and styling)
* added flags of countries to the index page (styling is implemented, but we can disclose it on click event, now is just opened all the time)
* about and guide view have been deleted and user Templateview instead (there is no need for this views if they are only showing template. Django has built in view for that)
* changed test a bit, bcs I have deleted a processor in web application and moved it to api application (the processor in question was get_event(), since this is a query for DB it should be in api app instead of web)