Update + Existing Features behavior on Releases Overview to be consistent with other Options for adding Features to this view

There are a couple of different ways of adding features to the Releases -> Overview/Roadmap views. The different approach have different behavior and the behavior for one of the methods is quite disruptive to the schedule. The scenarios apply when features are assigned to this view without having start on and/or due dates applied prior to. 

Option 1: Features Drawer Actions Menu -> Add to a Release Phase

The feature will automatically inherit a Start on and due on date that coincide with the duration of the phase you add it to. 

Option 2: Adding features to a Release and/or to a Release Phase from within the Releases -> Overview/Roadmap screens by clicking on the + Existing Feature button is disruptive to the current Gantt chart/schedule.  

• If you add a feature and specify a phase to add it to, it doesn't adhere to start and end of the phase like in option 1. Rather, it applies it at the end of the release and will push out the phase to the end of the release as well. If you add a feature or features without adding them to a phase, they end up pushing out the release date as each feature added is assigned a 5 day duration by default and they are staggered. 
• Desired behavior: If added to a Phase, have it behave the same as option 1 - the feature is assigned start and due on dates equivalent to phase start and due on dates. If not added to a phase, assign it a due on date that is the same as the release date.