StandardPanel's "More" button restyle

#### Purpose

Restyle "More" button. Add there information about count of hidden members.

#### Modifications

Added converter to compose "SHWO MORE (N)" text. Result of PR:
![001](https://cloud.githubusercontent.com/assets/8158551/5320130/e9c54276-7cb7-11e4-943b-246e356c8e9e.PNG)

#### Unit tests

For new converter added unit test.
![001](https://cloud.githubusercontent.com/assets/8158551/5320150/0dc8be3c-7cb8-11e4-91d8-1d512186b1d4.PNG)

#### Additional references

[MAGN-5558](http://adsk-oss.myjetbrains.com/youtrack/issue/MAGN-5558).

#### Reviewers

@ramramps, please, take a look.
@Benglin, FYI.