Merge pull request #2 from maerch/master

Styling of front page
Master branch now contains server file that keeps track of sessions (serverWithPregame.js)
Input field of the chat window will be cleared after message was sent
We now keep track of User objects in two hash tables whose keys are session IDs. Game should theoretically work.
Merge remote-tracking branch 'upstream/master'
Puts everything in a single react component