AppVeyor re-build by committers is enabled

[Sutou Kouhei]

Hi,

I asked INFRA to add the "arrow committers" GitHub team
to teams of the "ApacheSoftwareFoundation" AppVeyor account:

  https://issues.apache.org/jira/browse/INFRA-18930

Now, Apache Arrow committers can re-build AppVeyor jobs from
AppVeyor Web URI. AppVeyor jobs sometimes fail by network
trouble. Re-building will be useful for the case.

Note that we need to sign out and sign in again to reflect
this change.


Thanks,
--
kou