Add support for Big and Little Endian modifiers

This pull request also fixes encoding issues in existing tests caused by upgrading ruby from 1.8.7 to 1.9.3.
@Fryguy, @chessbyte please review.


Can you explain this?  Since specs run out of order, technically this is incorrect.  To do it correctly, you should create a second spec with two successive calls, or just do it twice in the same `it`.