68280644 Assign People on Tasks

 - added ability to assign multiple people on task
 - added displaying of assigned people on hove via bootstrap tooltip
 - added rspec tests
Merge pull request #55 from bitzesty/68280644-assign-people-to-tasks

68280644 Assign People on Tasks
68280686 Task deadlines implementation

- added deadline field via datepicker
- added displaying of deadline via tooltip