fix(file_list): Incorrect response after remove and add file

Remove and then immediately add same file can lead to
incorrect content in response. Because pending timeout after remove
may resolve early then file will be processed, and in response get not
processed content.
fix(config): #1113 Watching is not working properly on linux

Solve bug in watch service by using pooling

Closes #1113
Merge branch 'pr-1114' into presubmit-master-pr-1114
chore: release v0.12.20
fix(web-server): cache static files

Files in `karma/static/*` were always read from file system.
These files typically don’t change (except when developing Karma itself)
and so it makes sense to cache them in memory.
Especially `./static/context.html`, which is read for every test run.

The main reason for this change is that when using native events
(non-polling), watching can easily hit the EMFILE limit and then this
`fs.readFile()` can be super delayed. This was easily reproducible
problem in AngularJS test suite.
chore: release v0.12.21
fix(preprocessor): treat *.tgz, *.tbz2, *.txz & *.xz as binary

Tarballs often use extensions joined with used compression, e.g. *.tgz instead
of *.tar.bz.

Also, there is a new xz lossless compression format that is slower but gives
better results than gzip or bzip2.
docs(readme): svg badges
Merge pull request #1155 from sahat/patch-1

readme: svg badges
style(web-server): correct spelling in a log message.
docs: simplify npm test commands

This removes "node_modules/.bin" from the commands that run karma.

It is not necessary to specify the full path to karma since npm will
automatically add the "node_modules/.bin" directory to the front of
$PATH when it is running scripts.
Merge pull request #1162 from mgeisler/docs-simplify-npm-commands

docs: simplify npm test commands
Merge branch 'pr-1148' into presubmit-master-pr-1148
chore: release v0.12.22
docs: fixes typos and makes config filename consistent

There were some typos to be fixed in various places and there was also an
inconsistency with the name of the files used in intro/configuration.
Merge pull request #1165 from cirocosta/docs-typos-and-consistency

docs: fixes typos and makes config filename consistent
docs(dev): Clarify git commit message instructions.
Merge pull request #1161 from eventualbuddha/clarify-commit-conventions

docs(dev): Clarify git commit message instructions.
Merge pull request #1159 from eventualbuddha/fix-typo-in-log-message

style(web-server): correct spelling in a log message.
feat(init): install coffee-script automatically

if the user initialize Karma passing a .coffee file we'll install
coffee-script and put it as a dev-dependency

Closes #1152