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- buttons are .css and .ui based.

- .svg used as icons are set in .ui.

- .svg updated, filled circles removed.

- backgrounds and borders are set in .css.

- redundant and no-more-used code in callwidget.cpp/instantmessagingwidget.cpp removed.

Change-Id: I9c52801a49d503c3c6a7dc8df9ae02ff90bb6a67
Tuleap: #148