Currently if a user does not replace the .htaccess file with the new update this can lead to serious problems in case Apache is used as webserver.

This commit adds the version to the .htaccess file and the update routine fails in case not the newest version is specified in there. This obviously means that every release has to update the version specified in .htaccess as well. But I see no better solution for it.

Conflicts:
	lib/private/updater.php

The update routine tries to test the database migration before actually performing the update.

However, this will fail hard if the schema has changed (for example an unique key has been added). App developers can convert the DB in preupdate.php, however it is not called before and therefore the update fails.

This actually breaks ownCloud updates from ownCloud 6 to ownCloud 7 when the files_antivirus app is enabled.

Ref https://github.com/owncloud/core/issues/11078

We do not support updates from 6 to 8 directly, therefore we can remove those upgrade routines.

If an app upgrade failed, the core version will not be increased either
in the database. This will re-display the update page and make it
possible to redo the apps upgrade.

Note that any core repair routine must take into account that an update
might need to be redone again even though the core's DB state is already
the one of the new version.

The updater is using "before update" repair steps and "regular" repair
steps.
The "regular" repair steps are also used by the CLI tool.

Currently no steps exist but can be added later in the static methods in
the \OC\Repair class.

Added unit test to test messaging, error and exception cases.

adding auto increment/PK to table files_trash

adding PK to table ldap_user_mapping and ldap_group_members

adding PK to table ldap_group_mapping

truncate permissions table to allow smooth creation of primary key

adding unit test for creating an auto increment column on a table which already contains data

remove unneeded table files_trashsizes

fix unit test

no need to truncate *PREFIX*permissions

On Oracle adding auto increment columns is not working out of the box - Oracle migrations are to be done manually

Added "dry run" argument to only run the update simulation.
Added argument to disable migration (useful for bigger setups where
table duplication would take too much space)

When upgrade, also simulate the database schema update for apps before
doing the actual upgrade.

- Added app id in update overview.
- Added status message for disabled app for CLI upgrade and web upgrade

In environments where the data folder is mount from another partition,
it is important to check that the data folder we see is actually the
real one. If the mount failed for some reasons, this fix will make
ownCloud temporarily unavailable instead of causing unpredictable
behavior.

If trusted_domains is not set after a CLI upgrade, show a warning in the
output.

1. We're maintaining the same code twice which leads inevitably to problems as this one. The createHtaccess routine is only used to use the correct paths to the 404 and 403 document.
2. Updating the ownCloud instance as described in our documentation (`Delete everything from your ownCloud installation directory, except data and config.`) will break the links to the ErrorDocuments anyways and show the default error handlers if ownCloud is not installed in the root directory.

send the build number too to push the next daily build. This is needed for the new daily build update channel

Conflicts:
	lib/private/vcategories.php

revert changes to fbbc76f2 because master is very unstable right now