[WIP][FEATURE] Added item-table component for visually managing items

added item table component for managing items

__Tasks:__
- [ ] gather feedback for my changes

__Informations:__

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| Tests pass?   | none
| Fixed tickets | i hope so
| Doc           | none

__Requires:__
https://github.com/sulu-cmf/SuluSalesCoreBundle/pull/1

@turbo-ele round values because of float number problem in javascript and business rules (2 digits after comma and round up). Implement a function which rounds values (or use globalize?). This function should be located at a central place and should be configurable to change it quickly if needed...