extend testcases

This testcases are here to check special bit numbers like 100! and
leading zeros.
fix for leading zeros

fixes the problem for the leading zeros of value blocks
Merge pull request #2 from leobuettiker/master

Fix for missing leading zeros in toString implementation
Fixed formatting, cleaned up tests, updated minified file
Updated version number for npm
Improved pow performance by using repeated squaring
Fixed comparison of 0 and -0