/api/schedules does not support pagination

[kiyoto]

This issue is similar to Issue #1106 For a large Digdag deployment, it's possible that the user has more than 100 schedules. One approach, of course, is to deploy multiple Digdag servers. However, this is not practical for a hosted solution like Treasure Data's workflow (disclaimer: I work there)

[yoyama]

@kiyoto Same with #1106 . We will discuss about it.