Refactor generic options widget out of s17.app.taskmanager

[davilima6]

The main widget for s17.app.taskmanager is shared with other products - such as collective.polls - so making it standalone will make room for cleaner dependencies and adaptations. (was https://github.com/simplesconsultoria/s17.app.taskmanager/issues/1)

For instance, c.polls uses the tasks widget to allow users to edit options for a poll. Nevertheless each option is labelled "Add a new task" which is an usability problem.

[hvelarde]

I think this was implemented in 71136a3 ; let's ask @flecox and @Quimera