requirements.txt for installing packages for stools

For using stools, you may need to install some packages with
this requirements.txt

e.g.
$ pip install -r requirements.txt
describe what stools requires
fix: -r option is required to install requirements
import 'A Wordcloud in Python' by Peekaboo to make wordle like image

see following
a. http://peekaboo-vision.blogspot.com/2012/11/a-wordcloud-in-python.html
b. https://github.com/amueller/word_cloud
Add free font by google
fixed: font path
for saving time, pre-built so is added.

For saving time, pre-build so is addded. So, if you modify
query_integral_image.pyx, please do follow and use so file.

$ make

Also, if you want to update any .so file to commit, please do following
command due to .gitignore.

$ git add query_integral_image.so
$ git commit
update requirements.txt (Pillow for imaging)
can import wordcloud sub-package under stools package
generating wordcloud for clustered text

FIXME: need to arrange some lines to be more understandable and clear
fixed: trs does not use stemmer_name when it call trs_job with pool.map

see:
http://docs.python.org/2/library/functools.html#functools.partial
use snowball stemmer insted of lancaster for demo
change default image size to 800 x 400
fixed:difference between text in file and text for picture