Change in configuration

- remove “parent” in menu config
- add “children” in menu config for submenu
- add more menu option
    - linkAttributes
    - childrenAttributes
    - labelAttributes
    - displayChildren
    - attributes
- support submenu by using recursive config
Remove unused code from configuration

- Remove flatNode function
- Remove beforeNormalization
Check Permission for all node in menu tree
get route from RouteCollection
support controller in the service:method notation
Update Configuration Method Example
Update README.md
Merge pull request #2 from angonyfox/master

Support More Knp Menu item optioin