ME: included 'created_by' property in projects endpoint
ME: added a check for 'created_by' in 'test_projects_list' test case
ME: removed 'created_by' check to see if the test will still fail on travis
ME: added 'created_by' to excluded properties in project_serializer.py
ME: reverted to earlier changes; removed created_by from exclude property and added an assert in test_projects_list
Merge pull request #527 from onaio/526-return-project-creator-on-projects-endpoint

526 return project creator on projects endpoint