do not share users data with config files

Signed-off-by: Tigran Mkrtchyan <tigran.mkrtchyan@desy.de>

Whenever an exception occurs in the sabre connector code or code called
by it, it will be logged.

This plugin approach is needed because Sabre already catches exceptions
to return them to the client in the XML response, so they don't appear
logged in the web server log.

This will make it much easier to debug syncing issues.

Sometimes it's not possible to disable APC entirely and some of
apc_functions are disabled. Only thing which is possible is
to disable apc.enable option.

In environments where there are rules for the email addresses, the "from
address" that owncloud uses has to be configurable.

This patch adds a new configuration variable 'mail_from_address'.
If it is configured, owncloud will use this as the sender of *all*
emails. (OwnCloud uses 'sharing-noreply' and 'password-noreply' by
default). By using the 'mail_from_address' configuration, only this
email address will be used.

OC_Util::setupFS($user) will create a data dir for the given string - no matter if the user really exists - OCP\JSON::checkUserExists($owner); introduces a ready to use check which will bail out with an JSON error

This reverts commit 6254f0a4.

When calling fopen() on some storage types, these return false instead
of throwing an exception.

This fix makes sure that in case the stream wasn't opened (for example
when a file doesn't exist any more) the stream isn't wrapped.

Also added 'rb' as another case that doesn't need to be wrapped.

Fixes #6832

- 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

The encrypted size was used when calculating folder sizes.
This fix now also sums up the unencrypted size and shows that one when
available.

This fixes the issue introduced by the transfer id which itself wasn't
taken into account by the shortcut code for part file in the shared
storage class.

Storage mount points are not deletable, so make sure that the unlink
operation and its hooks aren't run in such cases.

Note that some storages might recursively delete their contents when
calling unlink on their root. This fix prevents that as well.