#285 Added ability to convert time based on time zone

Signed-off-by: Zhou Fang zhou.fang@eclipse-foundation.org

Can be previewed here:

https://deploy-preview-305--eclipsefdn-solstice-assets.netlify.app/time-conversion

and

https://deploy-preview-255--eclipsefdn-hugo-solstice-theme.netlify.app/components/agenda/#dynamic-time-based-on-users-timezone