on filtering the share box users and groups whose name begins with the search term shall appear on top, fixes #6430

Fix issue #6269

When session_keepalive is true (default) the heartbeat will be send as
often as the half of the session timeout value.

Note that it doesn't work 100% like the PHP functions so the tests
have TODO comments to fix those core functions eventually.

Tried to add more apps (others break).
"preprocessors" is now populated automatically based on the tested apps.

- Refactored download URL building to make it overridable
- Added download URL override in public page
- Added JS unit tests for download URL
- Added OC.redirect() method to facilitate unit testing

Makes it possible to create query strings by passing a JavaScript hash
map and automatically encodes the keys and values.

- added karma utility to run jasmine unit tests
- added Sinon library (for stubs/mocks/fakeserver)
- added a few unit tests for core and files
- added autotest-js.sh script

 * uses zxcvbn
 * outsourced to separate jquery plugin
 * async loading
 * hide strength meter if input is empty
 * feedback if user enters weakest password
 * fade in and out
 * show tipsy with strength
 * Opera 12, IE8-10, FF 23, Chromium 29

As suggested by @PVince81 : https://github.com/owncloud/core/pull/6721#issuecomment-32289922

This fix issue of calendar app with IE8, see issue report for details:
https://github.com/owncloud/calendar/issues/291

- Refactored file tr lookup into FileList.findFileEl that uses
  filterAttr to avoid escaping issues in jQuery selectors
- Fixed versions and sharing app to properly escape file names in
  attributes