use yyyy-MM-dd date format; fix animal filters

previously used dd/MM/yyyy for user-facing dates, which is confusing
for international users. using yyyy-MM-dd avoids any confusion.

replace our own javascript methods for date formatting with the
Moment.js library.

fix animal filters applied using CQL filters on analysis page.
we were previously including/showing all visible animals, rather
than those selected for the analysis (and that are also visible).

fix display of layer information so it only appears under the
animals selected in the analysis filter. the layer info will,
however, be included for animals that are not currently visible.

add min/max constraints on from/to date fields on search page.