Prevent disappearing profiles after cobblerd restart (#1030).

This diff makes the use of --parent and --distro mutually exclusive.
The consequence is that subprofiles always have the same distro as
the parent profile. I think this has been the intended behaviour
ever since subprofiles got introduced, now it's just better enforced.

This diff also checks for assciated subprofiles first when you try to
delete a parent profile, this should prevent data corruption. Of
course using the 'recursive' flag is still supported.

Cobbler-web has been adjusted to use the (safer) xapi_object_edit API
for the deletion of items.

Conflicts:
	cobbler/remote.py
	web/cobbler_web/views.py
Merge pull request #1087 from jmaas/release26

Prevent disappearing profiles after cobblerd restart (#1030).
Fix broken gitdate, gitstamp values in version file.
Merge pull request #1089 from jmaas/release26

Fix broken gitdate, gitstamp values in version file.
Make kickstart selectable from a pulldown list in cobbler-web (#991).
Merge pull request #1092 from jmaas/release26

Make kickstart selectable from a pulldown list in cobbler-web (#991).
The fix for #991 broke "image"; this patch fixes that.
Merge pull request #1097 from jmaas/release26

The fix for #991 broke "image"; this patch fixes that.
Minor adjustment to the error_page template (cobbler-web).
Merge pull request #1101 from jmaas/release26

Minor adjustment to the error_page template (cobbler-web).
Don't allow kickstarts in /etc/cobbler.
Merge pull request #1107 from jmaas/release26

Don't allow kickstarts in /etc/cobbler.
Add strict kickstart check in the API, again should fix #939.
Merge pull request #1110 from jmaas/release26

Add strict kickstart check in the API, again should fix #939.
Don't send the Puppet environment when system status is empty (#560).
Merge pull request #1113 from jmaas/release26

Don't send the Puppet environment when system status is empty (#560).
Prohibit object renaming through the modifty_item API (#1079).

The appropiate rename_* API's should be used for renaming objects.
Merge pull request #1114 from jmaas/release26

Prohibit object renaming through the modifty_item API (#1079).
Revert "Prohibit object renaming through the modifty_item API (#1079)."

This reverts commit 078b9c064c712a4ad35721b042ed1969f3d98730.
Merge pull request #1118 from jmaas/release26

Revert "Prohibit object renaming through the modifty_item API (#1079)."