fix two candidates bugs

[50584785] The quitted candidates shows in 'schedule interviews' page's combobox
[50159691] refine 'candidate detail/index' page to show overall status of the candidate
[50639633] status cannot be changed in 'final assessment' dialog

Signed-off-by: Henry Chen <hchen@vmware.com>
Merge branch 'master' of https://github.com/vmw-tmpst/heroapp-LetsHire into candidate

Signed-off-by: Henry Chen <hchen@vmware.com>

Conflicts:
	app/models/opening_candidate.rb
Merge pull request #213 from Henry-CF/candidate

fix several candidates bugs
[50584785] only schedule interview for candidates under interview status

Signed-off-by: Henry Chen <hchen@vmware.com>
several ability refine

[50584785] should only 'schedule interviews' for candidates within interview loop
[50711767] recruiter cannot select hiring manager in 'new job opening' page

Signed-off-by: Henry Chen <hchen@vmware.com>
[BUG 49742331] remove "Help" link from navbar

  still keep the static_pages#help page since we will add it back
  later
update unit test

Signed-off-by: Henry Chen <hchen@vmware.com>
Merge pull request #216 from Henry-CF/candidate

fix several capability bugs
[50159535] nothing happens by clicking ok button on schedule interviews page if no interview row added

Signed-off-by: Henry Chen <hchen@vmware.com>
Merge pull request #215 from Chunjie/master

[BUG 49742331] remove "Help" link from navbar
use another way to fix the previous bug

Signed-off-by: Henry Chen <hchen@vmware.com>
Merge pull request #217 from Henry-CF/candidate

[50159535] nothing happens by clicking ok button on schedule interviews ...