Removed identifiers from rule overview in HTML report

Identifiers are in result details, they take too much space in overview.
Rule result gets CSS treatment and a tooltip in result details in HTML report
Minor styling for result details of rules that need attention in HTML report
Fixed compliant / non-compliant icons to be glyphicons
Extra compliance state for just unknown rules in HTML report
Split header and footer code into xccdf-branding.xsl

xccdf-brainding.xsl is a file that can be patched by downstreams to
provide their own logos and other branding.
Embedded the OpenSCAP logo in xccdf-branding as a minified SVG
Initial work to bundle CSS and JS in a sane way, it's still a bit insane though
Bundle bootstrap.min.css and jquery.min.js as well but don't minify