StandardPanel's "More" button restyle

#### Purpose

Restyle "More" button. Add there information about count of hidden members.

#### Modifications

Added converter to compose "SHOW MORE (N)" text. Result of PR:
![001](https://cloud.githubusercontent.com/assets/8158551/5339256/0b70f2a4-7ee7-11e4-97d5-20c3b5917a28.PNG)

#### Additional references

[MAGN-5558](http://adsk-oss.myjetbrains.com/youtrack/issue/MAGN-5558).

#### Reviewers

@ramramps, please, take a look.
@Benglin, FYI.