JBIDE-17849 CSS Hyperlinks aren't working on non-WTP projects

CSS Files path resolution is fixed, CSS Hyperlink, Create New File Hyperlink are fixed
JUnit test is added in order to test CSS Stylesheets inclusion using absolute and relative URLs

Signed-off-by: vrubezhny <vrubezhny@exadel.com>
JBIDE-17920 Tag Libs are not added when externalizing strings