Merge branch 'release/2.4.0.1' into develop
Migrated nereid_activity_stream module to 2.6 #1245

* Migrated __init__.py, setup.py
* Renamed __tryton__.py to tryton.cfg and migrated to 2.6
* Migrated activity_stream.py
* Migrated all test cases.
* Fixed view activity_stream.xml

Review ID: 16001
Review ID: 19001
Merge pull request #17 from tarunbhardwaj/feature/task-1245

Migrated nereid_activity_stream module to 2.6 #1245
Forward port nereid-activity-stream patch #1525

This patch will clean the code and handle the case if object_ or target field
is unavailable in Activity.

Review ID: 240002
PEPification and Updated .travis.yml #1525

Cleaned code as per flake8 and updated travis.yml

Review ID: 240003
Merge pull request #20 from tarunbhardwaj/feature/task-1525

Forward port nereid-activity-stream with PEPification Feature/task 1525
Refactor the README
Refactor setup.py

* Remove unused commands
* Changes for metadata to appear for PYPI
Bump version to 2.6.1.0
Merge branch 'release/2.6.1.0'