Rename directories to be more in line with and ng-boilerplate and gradle/groovy projects

- [x] app -> src
- [x] dev -> build
- [x] bower_components -> bower
- [x] custom_components -> third-party
- [ ] dist -> 
- [x] script -> bin
- [ ] server ->
- [x] tasks -> grunt tasks
- [x] test -> tests
- [ ] test it

see https://github.com/ngbp/ng-boilerplate