artifact support to get both lwip and linux-auto logs to gcs

[jenniexie]

I've got artifacts work with gcs using travis-ci interface, PR is:
#182

I have tested on my repo, here is the link of test logs upload example on gcs:
https://pantheon.corp.google.com/storage/browser/openweave/happy-test-log/164/?project=openweave-test-project&authuser=0&organizationId=433637338589

I've enabled it for all branches, so it should upload logs automatically to gcs from PR branch as well.

Hope this effort will help debugging the test flakiness on travis-ci.

Please let me know if you have any questions.

Note: Content in .travis.yml got shift to front a little bit, that is done by command "travis setup gcs" during travis-ci/gcs setup, more info is in this link:
https://docs.travis-ci.com/user/deployment/gcs/

[codecov-io]

Codecov Report

Merging #182 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #182   +/-   ##
=======================================
  Coverage   54.22%   54.22%           
=======================================
  Files         326      326           
  Lines       55972    55972           
=======================================
  Hits        30353    30353           
  Misses      25619    25619

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[gerickson]

There are a lot of gratuitous white space diffs here. Can you unwind those so we are just getting the material changes. If you need to do a squash and force push after cleaning those up, please do (let me know if you need help with those).

[gerickson]

Overall, there's a lot of duplicated, and undocumented, copy-and-paste code in .travis/script.sh. Please identify and propose opportunities for refactoring that code into a common subroutine or common code with more documentation.

[jenniexie]

Overall, there's a lot of duplicated, and undocumented, copy-and-paste code in .travis/script.sh. Please identify and propose opportunities for refactoring that code into a common subroutine or common code with more documentation.

I am working on this one, I like this comment. I will move the common code into a bash function.

[jenniexie]

ping RS @robszewczyk, could you help with this PR? Thanks!