[BZ 1146228] - Metric detail hover is missing from graphs - this was caused by "! important" in style definition in patternfly.css because it overrided the elements style attribute (where we programatically set if the hover is shown of hidden). I've created a new css style called rhqHidden where the "! important" is not used.

(cherry picked from commit ff40ccfcac0ccabcf626f58c02ffb62476b6ea7f)
Signed-off-by: Libor Zoubek <lzoubek@redhat.com>

Conflicts:
	modules/enterprise/gui/coregui/src/main/webapp/org.rhq.coregui.CoreGUI/sc/skins/CoreGUI/skin_styles.css