Improve DNS diagnostics

This set of changes should make debugging kresd easier. The part with verbose logging is a bit hacky but we need to get things moving quickly to enable diagnosing problems with Google services.

added 7 commits

• 1bdcceed - diagnostics dns: log resolv.conf* even from /tmp
• 742eb4ce - diagnostics dns: log information about running resolver process
• 58c1c3b2 - diagnostics dns: use dig tool (if available)
• d170e6ff - diagnostics dns: Enable verbose logging in kresd
• 04312af6 - diagnostics dns: log relevant content from /var/log/message
• 23006936 - diagnostics dns: log parsed trust anchors from inside of kresd
• ba05b8e2 - diagnostics dns: attempt to resolve prominent web sites

Compare with previous version

Fine with me, merging, but just making sure that @shenek knows about it

merged

assigned to @shenek