Added Cmdline to procstat

[akrus]

Required for all PRs:

• Signed CLA.
• Associated README.md updated.
• Has appropriate unit tests.

As a first approach to #1873, this PR adds cmdline with full command line of process as field. Not sure what should be updated in README.md. Adding as a tag is easy, but needs test change, so I'm afraid I need some assistance there.

[scottprichard]

it looks like the unit tests didn't even run, some docker image was not found.. any ideas? I for one would like to see this feature in telegraf as I have had to push out a bunch of procstat config that will be completely unnecessary once this is in. So far I have only used it in test and would like to avoid pushing all that config into prod in favor of this.. Thanks for anyone who is working on this, you guys rock.

[glinton]

Apparently circle won't be able to build this until this branch gets updated with master.

[scottprichard]

hey @akrus looks like you need to pull master in and re-kick the build as @glinton mentioned. If you could that would be awesome, if not let us know and I'll fork it and sign that CLA and attempt to re-kick with your changes. Hopefully should be an easy merge if you haven't touched it since, which seems to be the case with your forked repo.

[glinton]

Closing in favor of #5681