chore(sauce): use tunnel-identifier and ready-file only on Travis

When running locally, there's not TRAVIS_JOB_NUMBER env variable defined and it screws
the Sauce Connect (it uses a tunnel with empty name), this makes it work locally without defining
TRAVIS_JOB_NUMBER env variable.

Also, if you run the sauce_connect_setup.sh locally, without having SAUCE_CONNECT_READY_FILE, it
does not pass the `--ready-file` argument to avoid Sauce Connect blowing up.
chore: update Karma to v0.10
chore: update Node.js on Travis
chore: disable npm install on Travis

Grunt is configured to run `npm install` before every task. That is convenient when switching a branch for example.

On Travis, this makes no sense and is causing tons of NPM warnings (eg. packages not defining repository field etc).
WIP: fiddling with travis config

WIP: start webserver

WIP: fix webserver task

WIP: fix typo

WIP: do not package before tests:docs

WIP: redirect sauce stderr into log file

WIP: merge

chore(travis): run the tasks synchronously