[Frontend] Styling Export button

fixes #973
- In progress:
- Added new download symbol to symbols font;
- Added export symbol to export button;
- Layout/markup/SASS for historical tabular
view modified;

platform/features/table/res/templates/mct-table.html

@@ -1,10 +1,8 @@
-<div class="l-local-controls">
-    <a class="t-btn l-btn s-btn"
-       ng-click="exportAsCSV()"
-       title="Export This View's Data">
-        Export
-    </a>
-</div>
+<a class="t-btn l-btn s-btn t-export"
+   ng-click="exportAsCSV()"
+   title="Export This View's Data">
+    Export
+</a>
 <div class="l-view-section scrolling" style="overflow: auto;">
     <table class="sizing-table">
         <tbody>