v1.1.0 - Refactor with 1.5X~ faster performance

1. Refactor the encoding code to be simpler and cleaner, as a bonus, it gives better
   performance which is 1.5X~ faster than the old.
2. Add a brief description of the algorithm and state the compatibility with other
   Base62 implementations.

v1.0.0: release 1.0.0

Change-Id: I98dacf56cb46730dbb4ab6e347b6dda4204de6c0