Add initial chart generator python file.

Followings are steps to install pygan and dependent libraries in Ubuntu:

$ wget http://peak.telecommunity.com/dist/ez_setup.py
$ sudo python sz_setup.py
$ sudo easy_install pip
$ sudo apt-get install python-dev
$ sudo apt-get install libxml2-dev libxslt-dev
$ sudo pip install pygal
$ sudo pip install CairoSVG tinycss cssselect # for PNG output
Append XY Chart sample code
Priotize top risky items among all repositories.

You can use, just, 'run.batch.at' script at the top of target project. It'll scan all repositories and run 'churn.ccn.analyzer.pl' script onto each git repository internally. And it'll gather all 'file_churn_complexity.csv' and sorted by churn (commits) and file complexity descending order. Finally it'll export top risky items to be reviewed or refactored to 'top_risk_files.csv'.
Renaming scan.at.pl to scan.all.repos.at.pl to represent clear meaning.
Modify README file
Removing global variable for using comparator.

By passing hash object parameter to comparator explicitly.
Support generating chart automatically by using python library.

It depends on two famous python library:

   - pandas  - data analysis library (http://pandas.pydata.org/)
   - pygal   - chart svg chart creator (http://pygal.org)
Merge branch 'feature/generate_chart' into feature/top-risk-list
Collecting all 'churn-complexity.csv' file for all repos in a project and Generate chart as result.
Renaming shell script ext name