* Remove six for PY2 compatability since our dependencies are not, PY2
is legacy.
* Removed usages of utils from future/past libraries since they are
deprecated. This includes 'from __future__ ...' and 'from past...'
statements.
* Removed compatibility imports for PY2, switched from six imports to
standard library imports.
* Removed utils code blocks that handle operations depending on PY2/3
versions.
* Removed 'from __future__ ...' lines from templates/code generators
* Used PY3 syntaxes in place of PY2 compatible blocks. eg: metaclass
* Removed comment_type 'updated'
* New doctype activity log
* Moved feed.py to activity_log
* Updated feed gets stored in activity_log
* Activity page fetches feed from activity_log
* feed match condition change
* modified
* modified hooks.py
* modified sessions.py
* patch added
* naming in patch
* moved login, logout feed to activity_log
* changes in auth.py, hooks.py
* deleted doctype authentication_log and added test cases
* added utils.py in core
* moved some methods from communication.py to utils.py
