Bug 901168 - Tapping the center of the screen while receiving a call leaves the call in an unanswerable state
Bug 920948 - [Bug] Sometimes drag&drop is not working fine with collections
Bug 885713 - propose a "make hint" that would use jshint instead of gjslint r=ochameau,rik f=jlal

This adds
* a default .jshintrc configuration file
* a `make hint` launcher
* a way to launch the linters (including the old lint linter) for a specific app
  only.
* you can also use another jshint configuration file
* use .jshintignore file as main exclude file, from both gjslint and jshint
* the pre-commit hook uses a makefile goal now
* remove the node_modules directory in really_clean
* use real files instead of phony targets for node modules and git hooks
* revert the part of bug 918295 affecting the git hook copy
Merge pull request #12248 from julienw/885713-jshint

Bug 885713 - propose a "make hint" that would use jshint instead of gjsl...
Bug 906316 - Don't download the xulrunner SDK each time we change a branch if their configuration are different r=yurenju,asuth,ochameau

This also shows a message when the archive file seems to be corrupted, advising
to run "make really-clean". Also changed "make really-clean" to remove all
xulrunner related files.

We now uncompress the archive directly in a specific directory that should
change when we change the URL.

We use a dot file inside the xulrunner SDK directory to keep the URL used to
download that SDK.

Now we can also define XULRUNNER_DIRECTORY from the command-line. If not
defined, it will use the default xulrunner-sdk-26/xulrunner-sdk.
We can also define XULRUNNER_BASE_DIRECTORY which is the place where the
XULRunner SDK will get uncompressed.

We export the new XULRUNNER_DIRECTORY variable along with the
existing various xulrunner program paths. These paths have been made absolute
using make's `abspath` operation.

The patch also removes the ./ prefixes to those paths as they're likely useless
and prevent from using an absolute path when defining XULRUNNER_DIRECTORY from
the command line.

This patch also remove the email's build_stage directory when running "make
clean".

This _will_ make all devs redownload XULRunner, sorry.

This make the build fail if submakes fail

Also add documentation at the top of the Makefile.
Merge pull request #12469 from crdlc/bug-920948

Bug 920948 - [Bug] Sometimes drag&drop is not working fine with collections
Merge pull request #12445 from Rik/incoming-tap-screen-901168

Bug 901168 - Tapping the center of the screen while receiving a call lea... r=etienne