Making a token expiration time configurable

This time should be configurable, so that it may be increased untill the
refresh token is supported. The defalult value is still 3600 secons to
match the standard.

This change also fixes small issue with oslo.config in storyboard-api
entry point.

Change-Id: Ib4d31c90e42e5180a9b891fe0d2c9eeb780ca7ee
Merge "Making a token expiration time configurable"