Merge branch 'release/2.6.3.0' into develop
Avoid duplicate commit information on task #2285

* This patch searches for commit_id for specific task, if true then
  continue, else creates commit information on task

Task ID: project-7/task-2285
Issue ID: 321003
Merge pull request #35 from simmianand/feature/task-2285

Avoid duplicate commit information on task #2285
Flake8ify nereid_project #2218

Task ID: project-7/task-2218

Review ID: 343001
Merge pull request #34 from Abhisar/feature/task-2218

Flake8ify nereid_project
Improve Serialisation of objects
Add _json to attachment and commits
Fix field name for serialisation
Add more information to XHR responses
Improvement to create tasks over XHR
XHR response on project
Flake8ify
Create a unique constraint on project and nereid user #2244

Task ID: 2244
Merge pull request #37 from Abhisar/feature/task-2244

Create a unique constraint on project and nereid user #2244
Allow filtering by the tasks you are watching #2441
Activity stream for commit on task #2282

This patch has added activity stream for each commit on task.

Review ID: 420005
Merge pull request #39 from priyankarani/feature/task-2282

Activity stream for commit on task #2282
More XHR improvements
Migration to 2.8 #2089

Review ID: 303003
Bump version to 2.6.4.0