updated prerequisites

prerequisites.txt

-httplib2
-lxml
-pyxnat
-requests
-pydash
-matplotlib
-flask
+Flask==0.10.1
+itsdangerous==0.24
+Jinja2==2.7.3
+MarkupSafe==0.23
+matplotlib==1.4.3
+nose==1.3.7
+numpy==1.9.2
+pyparsing==2.0.3
+python-dateutil==2.4.2
+pytz==2015.4
+requests==2.7.0
+six==1.9.0
+Werkzeug==0.10.4