Build: Restore minification for IE8

- Use compatibility mode for minification, although this still produces
some incompatible CSS
- Move all "@" keywords to newlines so that when IE8 stops processing
the unknown CSS it doesn't drop other CSS on the line
- Bump cssmin to the latest version. Note the "^" selector is the new
default for NPM and needs later versions of NPM to understand.
Datepicker: Initial documentation
Merge pull request #4779 from berubs/doc-datepicker

Datepicker: Initial documentation
Events Calendar: Initial documentation
Set font weight to 700 for all headings (fixes wet-boew/GCWeb#556)
Merge pull request #4782 from pjackson28/boldheadingsbydefault

Set font weight to 700 for all headings (fixes wet-boew/GCWeb#556)
Point the i18n assemble module to npm
Events Calendar: Removed duplicate </table>
Merge pull request #4784 from LaurentGoderre/assemble-plugin-npm

Point the i18n assemble module to npm
Merge pull request #4781 from berubs/doc-cal-events

Events Calendar: Initial documentation
Merge pull request #4786 from berubs/dup-table

Events Calendar: Removed duplicate </table>
Extended font weight 700 to heading classes
Merge pull request #4787 from pjackson28/fix700weightheadings

Extended font weight 700 to heading classes
WET theme: Fixed background colour of navcurr menubar item when open
Linting: Clean up spacing in handlebars templates
Merge pull request #4788 from pjackson28/fixmenbar

WET theme: Fixed background colour of navcurr menubar item when open
Merge pull request #4789 from nschonni/v4-spacing-cleanup

Linting: Clean up spacing in handlebars templates
Merge pull request #4750 from nschonni/v4-ie8-css-minification

Build: Restore minification for IE8
Zebra - Improved documentation - Fix #4777 and #4778
Merge pull request #4793 from duboisp/v4.0

Zebra - Improved documentation - Fix #4777 and #4778