[DF-1534] Changed selection mode to single selection.
Merge branch 'framework_0_5_5' of https://github.com/dava/dava.framework into framework_0_5_5
Merge branch 'framework_0_5_5' of https://github.com/dava/dava.framework into framework_0_5_5
[DF-1534] Fixed item selection on Drag'n'drop