public long getCurrentTimeMillis() {
    return System.currentTimeMillis();
  }
Class created to add testability in terms of time usage. Using this wrapper of
System.currentTimeMillis instead of use the System call directly we improve our code
testability and provide mocked implementations of TimeProvider with pre-configured results.

@author Pedro Vicente Gomez Sanchez.
lynx/src/main/java/com/github/pedrovgs/lynx/model/TimeProvider.java