#3: Replace react.createClass with ES6 class (closes #3)

[FrancescoCioria]

Issue #3

Test Plan

tests performed

npm start -> no errors

tests not performed (domain coverage)

At times not everything can be tested, and writing what hasn't been tested is just as important as writing what has been tested.

An example of partial test is a field displaying 4 possible values. If 3 values are tested, with screenshots, and 1 is not, then it should be mentioned here.}

[nemobot]