Based on the instruction on https://github.com/mde/timezone-js adding all timezones
Added timezone conversion feature.
Timezone has been introduced in dashboard configuration. As this is the common setting to be used across panels viz. table, histogram and timepicker.
In table configuration, added support to define timeformat
From histogram removed timezone setting and pointed to use the dashboard one.
In config.js, specify timezone directory according to server (and hence modified settings.js) Not required zones can be removed.
Changed default in settings and config