Update histogram.py

fixed typos in help message
Merge pull request #13 from phillipkent/master

Update histogram.py
Added the ability to take in aggregated data in bar_chart, and updated
the documentation along with it.
new option: sort by numeric keys

If input file was list of number, sort_keys would sort by ascii rules: 1,10,15,2,22,3,36. The new option will sort this list numerically: 1,2,3,10,15,22,36.
use ∎ instead of *
use ∎ instead of *
Added utf8 encoding header.

0a8dfb890f9e introduced non-ascii characters in the source file, causing:

    SyntaxError: Non-ASCII character '\xe2' in file data_hacks/histogram.py on line 188, but no encoding declared; see http://www.python.org/peps/pep-0263.html for details
Added utf8 encoding header.

0a8dfb8 introduced non-ascii characters in the source file, causing:

    SyntaxError: Non-ASCII character '\xe2' in file data_hacks/histogram.py on line 188, but no encoding declared; see http://www.python.org/peps/pep-0263.html for details
Merge pull request #15 from erikvanzijst/patch-1

Added utf8 encoding header.
add pre-aggregate support for histogram
Merge pull request #17 from jehiah/histogram_agg_17

Support ingesting Aggregate data from histogram.py
add option to list out percentage
doc updates
Merge pull request #19 from jehiah/bar_chart_percentage_19

bar chart/histogram percentage