Implement animation in the level buttons as proposed in the design

The buttons wiggles, grow to 150% and settles down
to 125% of the original size.
Separate WordListView in his own js file
Remove unneded files

These files where included by mistake in the web activty skeleton
from the GetThingsDone activity
Separate MatrixView in his own js file
Use a matrix instead of a array to store the references to the Text elements
Start animation on hover in the matrix

A array store the letters where the effect should be applied.
This patch just change visibility over the letters in the matrix,
the tween is not applied yet.
Restore letters in the matrix after hide them for animation
Animate selected letters