First files for listdir tests
First swing at the listdir function, re: #16

Walks a directory tree and returns 2-tuples of: path to discovered
file and a bitmath instance of the size of the file.
More tests for listdir
Add test files for getsize
Tests for filtering with listdir
Fix unit tests, re: #20. Formatting
Fixes/updates to listdir, and string representation

* listdir supports the 'filter' parameter now
* listdir properly sorts out links from files
* listdir allows you to return the relative path OR the absolute path
Python 3.3 support

Thanks to @davidfischer-ch for the PR

Closes #2
Closes #5

Now supports proper __truediv__ in 2.x and 3.x for num/bm and num/bm
Update real_life_examples.rst

Fixed unit mismatch in Example 1
Update README with scientific string format
Implement singular/plural unit notation
Hopefully help make travis handle python3 nosetests
Merge branch 'getsizelistdir'
Update gitignore
Update travis to run two separate builds in the matrix.

One for python 2.7 with the 'ci' make target
One for python 3.3 with the 'ci3' make target
Merge remote-tracking branch 'hikus/patch-1'
Merge remote-tracking branch 'david/pretty'

Conflicts:
	bitmath/__init__.py
	tests/test_representation.py