docs: fix a typo in plugins page.

docs: fix a typo in plugins page.
change 'chroma' to 'chrome'
docs(migration): module.export/module.exports

Change code snippet to use module.exports rather than module.export, because that's what the runner expects, and previous sample code doesn't work from copy-paste.
chore(config): cli instructions

Updates reference from karma object to config object.
fix(static): Use full height for the iFrame.
Fix based on PR #714.
docs(config): Fix the browser/plugin list in the config file documentation.
docs(config): fix a typo
style(config.tpl): add note about installation of launcher plugins
fix(watcher): improve watching efficiency

This fix significantly improves watching performance. It tells chokidar to
ignore all paths that do not match any of the watched patterns.

Before we were only ignoring paths that match some of the excludes patterns.
That means that even files that didn't match any of the watched patterns were
still watched by chokidar and ignored on the level of `fileList`.

Note, this fix requires chokidar 0.7.0

Closes #616
feat(watcher): ignore initial "add" events

Initially all the patterns are scanned using glob. Then we start watching then
with chokidar. Chokidar now allows to ignore initial "add" event, which was
ignored by the fileList anyway.
fix(watcher): ignore double "add" events

On linux, `fs.watch` (which chokidar uses when `usePolling: false`)
fires "add" events twice. This change makes `fileList` to ignore the
second event.
chore: add CLA into contributing docs