Population of Classes in UI

#### Purpose

Using styles from https://github.com/Benglin/Dynamo/pull/104 should populated found classes for `LibrarySearchView`. Styles can be changed as we don't have final design.

#### Modifications

Added ListView for Classes collection.

#### Additional references

[MAGN-4808](http://adsk-oss.myjetbrains.com/youtrack/issue/MAGN-4808).

NB! This PR must be merged after https://github.com/Benglin/Dynamo/pull/104.

#### Reviewers

@Benglin, please take a look.

Does everything still work if we return ```IEnumerable<BrowserItem>```? Or it must be ```ObservableCollection<BrowserItem>```? If ```IEnumerable``` works, please remember to update it to use that.