Bug 1219889 - Travis: Break out the linter steps to their own job
Bug 1219889 - Travis: Break out the linter steps to their own job

Since this job sets `sudo: false`, it will run on the container infra,
so be able to use caching. The `env: linters` is so that a nice label
appears in the Travis sub-job UI, eg see:
https://travis-ci.org/mozilla/treeherder/builds/87763293

We install the full set of node and python dependencies, since
hardcoding just the packages we need here could lead to the versions
getting out of sync with package.json/the pip requirements files. In
addition isort requires a populated virtualenv, and npm sucks if
passing package names directly (it reinstalls them even if installed).
It's worth noting that with the cache, full dependency installation
only takes 2.5s, so this is all moot.

This job (once it has populated the cache) now only takes 24s
end-to-end, whereas previously it would have been ~3.5 mins before the
linters steps had completed.

parkouss/treeherder,akhileshpillai/treeherder,glenn124f/treeherder,KWierso/treeherder,sylvestre/treeherder,glenn124f/treeherder,gbrmachado/treeherder,kapy2010/treeherder,kapy2010/treeherder,edmorley/treeherder,akhileshpillai/treeherder,edmorley/treeherder,KWierso/treeherder,avih/treeherder,wlach/treeherder,gbrmachado/treeherder,avih/treeherder,parkouss/treeherder,parkouss/treeherder,edmorley/treeherder,parkouss/treeherder,tojonmz/treeherder,sylvestre/treeherder,sylvestre/treeherder,kapy2010/treeherder,avih/treeherder,parkouss/treeherder,akhileshpillai/treeherder,sylvestre/treeherder,gbrmachado/treeherder,avih/treeherder,akhileshpillai/treeherder,tojonmz/treeherder,KWierso/treeherder,tojonmz/treeherder,wlach/treeherder,wlach/treeherder,avih/treeherder,tojon/treeherder,tojon/treeherder,sylvestre/treeherder,tojonmz/treeherder,KWierso/treeherder,parkouss/treeherder,tojon/treeherder,sylvestre/treeherder,tojonmz/treeherder,gbrmachado/treeherder,avih/treeherder,glenn124f/treeherder,gbrmachado/treeherder,edmorley/treeherder,glenn124f/treeherder,akhileshpillai/treeherder,wlach/treeherder,wlach/treeherder,gbrmachado/treeherder,wlach/treeherder,tojon/treeherder,kapy2010/treeherder,kapy2010/treeherder,glenn124f/treeherder,glenn124f/treeherder,akhileshpillai/treeherder,tojonmz/treeherder