Basic examples for developers

## Desc

Elvis is extremely basic for now, add more useful features for developers

## Examples

+ [x] hello-world
+ [x] Counter APP
+ [x] Router APP
+ [ ] TODOMVC
+ [ ] Blog Template

## Products

+ [ ] rust.cc client
+ [ ] markdown book

## Deps

To implement the examples above, Elvis needs to add:
+ [x] router
+ [ ] state machine in production
+ [x] gesture event driver

