admin: bump version numbers
admin: update cheshire3 version requirement
remove spurious line of code
report dynamic available operation when invalid op given
add system info page to search app

Add a page for reporting useful system information when diagnosing
problems. Currently page reports only the install versions of
`cheshire3` and `archiveshub`
disable email repository links when matches example.com
fix utility bar email repository link (issue 864)

Have WSGI apps fetch local mercurial contributors.json instead of
from URL.
docs: update release date in README
Merge branch 'hotfix/3.2.3'