Added a taglib for tweet

Added a tag that displays the correct
alert type/message. Modified user/index
to use this tag.
Added a tag to convert date to elapsed time
Added default sorting of tweets
Added support for followers and groups

App currently functions the same as before (modifying
the person to use name instead of first/last name). The
app compiles and works, but no functionality to actually
add a group or follow someone has been implemented yet.
Added auto-generated test classes for Group/Person