xmlui: Add initial Bioversity theme
xmlui: Fix banner image for Bioversity

Rename to "banner.jpg" to be more generic (we obviously know it's
for Bioversity), and fix the header CSS to match the actual size
of the image.
xmlui: Quick fixes to Bioversity XSL
xmlui: Quick fixes to Bioversity theme based on latest Mirage

This is just a re-sync with DSpace 3.1's Mirage, as we were missing
lots of little things (minor syntax fixes, new features, assets like
PNGs for features, etc).
xmlui: Remove unneeded image from Bioversity theme
xmlui: Tweak some colors in Bioversity theme

Borrowed from CSS on http://www.bioversityinternational.org/
Remaining changes for Bioversity XMLUI theme

Input forms and strings
input-forms.xml: Fix typo
input-forms.xml: Fix Bioversity forms typo

Biodiversity -> Bioversity
input-forms.xml: Remove Bioversity-specific form

We will use the generic CGSpace form.
input-forms.xml: Update Bioversity subject list