Shortened animation time between phases

+ changed from 50ms to 25ms between update calls.
Improved card animation performance

+ Cards now animate smoother and faster
+ removed redundant computations performed each frame
Additional comment

+ Added additional comment explaining what DELTA is.
Updated static variable name

+ Updated DELTA variable to more suitable name:
ROTATION_DEGREES_PER_FRAME
Merge pull request #378 from poixen/animation

Card Animation performance improvement