Bug 961039 - Xfail test_cost_control_data_alert_mobile
Bug 881957 - Implement toast and show toast after successfully change PIN
Merge pull request #15464 from viorelaioia/bug_961039

Bug 961039 - Xfail test_cost_control_data_alert_mobile
Merge pull request #13685 from dwi2/bug881957

Bug 881957 - Implement toast and show toast after successfully change PIN
Bug 937431 - [Tooling] make jshint a requirement on pre-commit r=rik

* changes how `make lint` works
* introduces a jshint-blacklisted reporter
* changes the pre-commit hook to run both jshint and gjslint
* changes the linter Travis job
Follow-ups:

Travis:
* one travis job

Makefile:
* do not try to lint non-existent files

Hook:
* use the jshint executable directly in the hook, so that we never run npm
  install when we just want to commit
* always run both gjslint and jshint, even if one of them fails
* use NO_XFAIL=1 because we already warn about xfailed files
* use LC_ALL=C so that sorting is the same for all platforms

Various:
* move the jshint-specific files to directory build/jshint/
* various other small changes
* update the xfail list
Follow-ups:

jshint configuration:
* remove all predefined globals from the main .jshintrc default global
* add new jshintrc files for subdirectories

Hook:
* fix the commit hook to fail when jshint is absent
* bailout early if we don't have xfail.list

Makefile:
* add documentation at the top of the Makefile
* fix Makefile for Mac OS X and other BSD system: don't use `xargs -d`
* support VERBOSE=1 when running make hint

General:
* fix the xfail list sorting and generate a current list
* add the README file