tasks #6614: style aggregates

Note: Cannot remove the aggregate line for now as we need it when we add
a new column.

+ remove yellow color for masschange
+ change style of masschange btn

Change-Id: I9053877da7b1479ceaee2487878c05a2f40cf763
Merge commit 'refs/changes/65/2265/7' of ssh://gerrit.tuleap.net:29418/tuleap into stable

* ssh://gerrit.tuleap.net:29418/tuleap:
  tasks #6614: style aggregates
This is Tuleap 6.12.99.47

Change-Id: Ic35661f906e5ebdeaa1f7b6f6d470b0c7c0d0c41