[50238471] disable 'schedule new' button when appicable

When candidate isn't in an interview status, such as marked-as-fail ready, the 'schedule
new' button should be invisible.

Signed-off-by: Henry Chen <hchen@vmware.com>
Merge branch 'master' of https://github.com/vmw-tmpst/heroapp-LetsHire
Merge pull request #174 from Henry-CF/sched

[50238471] disable 'schedule new' button when applicable