Write informational output to stderr for tail and search

[ghost]

Plaintext summary lines, 'no result' lines, and internal errors are sent to stderr to not interfere with actual data for tail and search.
This also fixes #42 where piping output from tail and search under json flag would break due to summary line.

Before

logdna search "docker" -j | jq
parse error: Invalid numeric literal at line 1, column 7

After

logdna search "docker" -j | jq
search finished: 5000 line(s). hosts: all. apps: all. levels: all. tags: all. query: docker
{
  ...json output
}

[jakedipity]

utils.log seems to have some handling when console.log fails. I'm assuming that was added on purpose due to some issue, so I think we should try to respect that as well.

[ghost]

fixed

[smusali]

I don't seem to understand why we are printing informational statements out to stderr for just solving non-JSON summary line interference; there are multiple other options:

• making the summary line itself a JSON since it has <key>: <value> pairs
• or with an extra parameter, making it disappear or appear, with something like --quiet or --noSummary

[smusali]

@ydshah2, can you mention this PR (#43) in #42 by saying this PR is intended to solve the issue? Thanks a lot in advance!

[ghost]

Adding discussions with @matt-march and @andkon, the change is not just to fix #42. That is what started the discussion. It is a move towards good design across the board. We are also keeping the stderr for internal output for both json and regular usecase for the sake of consistency. It is in line with what tools like curl do - something people are already familiar with. This will be a breaking change, and the version change will reflect that but the idea is to just do it the right way rather than add a flag just to satisfy the issue or for not being breaking.

[smusali]

Okay, just 2 requests:

• including console.error addition into utils.log instead of creating utils.error
• adding unit test cases for utils.log for now

Since we have never had unit tests for LogDNA CLI, we can start from here, at least, and then expand.

[smusali]

small requests again

[smusali]

lgtm!

[smusali]

loved very last change