Added basic server capability
Added abitlity to get older tweets from a specific user
Added mainclass initialization at jar generation
Fixed typo in twitter client
Added basic Javadoc for TwitterServer
Changed active to wait to scanner reading

The server now waits for input and stops running when receiving an EOF
signal.
Final touch to README
Fix empty user tweet list

Fixed a bug that would make the client crash when listing tweets from a
user that has none.