Implement menu bar with Sub-levels #322

Alongside the implementation of the new menu bar, some of the old icons
have been replaced. Fontawesome, the icon library has also been updated.

The Project & Team Selection 'selects' won't work here. They are just
placeholders. Someone needs to update these two placeholders.

@riz-hossain  @minar09  @Taitalus  Please test and report.