Add Symlink Support to Dolphin Overlay Plugin

This displayName() seemed to be based on Account::user() which used
to call _credentials->user(). But then we repurposed user() to be
davUser() and this usage wasn't updated to point back to the username
used for the credentials.

slotUrlEditFinished() is called when the wizard is triggered in
some situations.

Some custom server use persistent cookies with the auth token. So we should
clear all the cookies when disconnecting.
Account::clearCookieJar is only called from the HTTPCredentials. This funciton
is not used for shibboleth.
There is probably no reasons to keep the HTTP cookie anyway.

Issue #5370

This actually happens in low-disk situations.

Also retry creating it before each sync.

See #5317

Like "folder doesn't exist" - such that we will detect when the folder
becomes available and start syncing.

See #5317

The re-enables the UI, uses Qt API for importing and
stores the certificate/key in the system keychain.
People who had set up client certs need to re-setup the account. This is ok
since it was an undocumented feature anyway.

Fixes #5408 #5407.

The problem was that cleanup of the credentials page set the
credentials of the account back to dummy, thereby overriding
things like shib usernames.

This should be broken since a932eac8.

Currently, if get_git_head_revision() doesn't define GIT_SHA1 (which it
doesn't in some cases) it's possible to end up with the following error:

    CMake Error at CMakeLists.txt:69 (if):
      if given arguments:

        "STREQUAL" "GITDIR-NOTFOUND"

      Unknown arguments specified

Fix this by making sure both left and right hand arguments to STREQUAL
are always strings, even if GIT_SHA1 is undefined.

Signed-off-by: Kyle Fazzari <kyle@canonical.com>

To 2 MB/s and 10 files/s.

Reported in the doc repo owncloud/documentation#1618
This version as suggested by @jturcotte

An experimental fix for the issue, merged because it's low risk and
makes testing easier.

Otherwise it might happen that the model is inconsistant and this can
lead to crash in the worst case.

(For example, if there was a "fetching" label, and we hide it because it
was a 404. In this case, we would not call begin/endRemoveRows, so the
view could still call the model with an index of row 0, that used to be
for the label, but now correspond to the first element of _subs. And
because _subs is empty, this could lead to crashes)