[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>
update unit test

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

fix several capability bugs