Make push log "flags", "reject code" human readable; add crumbs to pull/push logs

Summary:
Depends on D18972. Ref T13049.

Currently, the "flags" columns renders an inscrutible bitmask which you have to go hunt down in the code. Show a list of flags in human-readable text instead.

The "code" column renders a meaningless integer code. Show a text description instead.

The pull logs and push logs pages don't have a crumb to go back up out of the current query. Add one.

Test Plan: Viewed push logs, no more arcane numbers. Saw and clicked crumbs on each log page.

Reviewers: amckinley

Reviewed By: amckinley

Maniphest Tasks: T13049

Differential Revision: https://secure.phabricator.com/D18973