HTTP Credentials: Read the password from the old location if not found.

Earlier clients used QtKeychain without a QSettings object, which made
QtKeychain to write the password encrypted into a settings default
location, ie. the registry under windows.

If we can not find a password at the new location it is tried to read
the password from the old default location once. That makes people
happy in migration scenarios.
HTTP Creds: In case of Keychain error, open the interact password dialog

But in case the user clicks cancel in the interactive dialog, invalidate
the credentials. Emit fechted() also in error case.
shibboleth: Fix the waiting curser that would not disapear

Fix #1915
propagator_qnam: Avoid using too much memory

The idea here was that the buffer would be maximum 8KiB, not minimum.
ProtocolWidget: limit the number of items

That should save memory instead of letting the number of items grow
to infinity
Fix build with TOKEN_ONLY_AUTH

It was broken by commit 6ff38d80053e469ee0a5d11498555d5a2fd913c0
Propagator: Fix crash when logging out during upload

Fixes #1957
FolderMan: Unload folder method added.

unloadFolder now correctly removes a folder from all maps and signal
mappers.
propagator_qnam Fix signal slot connection

Fix the signature so it can be connected

This was hapenning if the derver does not support X-OC-MTime

issue #1963
Use another way to detect that the server was reconfigured

Before, we would only detect it if all the files were removed, and no
file where added or changed. This may not be enough because there might
be a welcome.txt file. Now, we check that none of the file stays the same,
and some files are removed.

Relates issue #1948
[tx-robot] updated from transifex
tests: do not use system any more to modify files, rather perl native.
FolderMan: More useful logging.
tests: Reverted previous change, do not append in createLocalFile()
tests: Fix assertion.
[tx-robot] updated from transifex
Use file size of factor of four because of the createLocalFile algorithm
propagator_qnam: fix warning
Added XCode file.