feature/menu_item_level_changes

1) added attribute "hasOneChild"(default false) to Tent.Application.MenuItemView
2) added a check in function checkChildEntitlements: if no of entitled child views is 1 then set "hasOneChild" to true
3) added a check in menu_item handlebar :if hasOneChild is true then display the child view in the main menu itself.
4) Prevent url routing twice by menu

https://www.pivotaltracker.com/s/projects/896548/stories/61909546
https://www.pivotaltracker.com/s/projects/896548/stories/61970006

__General Requirements__
- [x] Pull Request contains full description of changes
- [x] Link to the Pivotal Tracker story
- [x] Rebased against latest master branch
- [x] There are no `-1` code reviews (can only be overridden by Kyle)

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__Coding Standards__
- [ ] Style guidelines are followed, code has been formatted
- [ ] Code follows idiomatic language paradigms

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__Testing__
- [ ] Test coverage has not decreased
- [ ] There is no performance degradation
- [ ] All appropriate automated tests are present
- [ ] Appropriate seed data exists


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__Documentation__
- [ ] Major design decisions have been documented on the wiki
- [ ] Deployment impact (changes required for new services, configuration, etc.)
- [ ] documentation links from Pull Request

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__UI/UX__
- [ ] applicable (UI/UX has been changed)
- [ ] reviewed for usability and design
- [ ] functions on 1024*768 browser size
- [ ] works on IE8

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__Shared Project / Dependencies__
- [ ] Reviewed by Architect
- [ ] API changes to shared components documented on wiki
- [ ] 3rd-party library introduced:
- [ ] explanation for updating a project dependency (e.g. 'latest version fixes a bug')

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__Defect__
- [ ] Feature or defect resolution has been manually tested and meets all requirements of the underlying story
- [ ] Seed data sufficient to satisfy testing resolution of defect
- [ ] Root cause analysis provided