request #6877: Red cross to delete artifact from its parent is almost invisible on Google Chrome

+ moving artifact icons to /images/ic

Change-Id: If0cd705ee08c922561aa64fe87f2f3e050e2e84f
Merge commit 'refs/changes/37/2437/2' of http://gerrit.tuleap.net/tuleap into HEAD

* http://gerrit.tuleap.net/tuleap:
  request #6877: Red cross to delete artifact from its parent is almost invisible on Google Chrome

Change-Id: I9725043a03f36db8c42a3fdd28b074b5af121f89
This is Tuleap 7.0.99.18

Change-Id: Ib8b33707d64ddd31d61af60885776a849452be39