spacemanager: Add missing update of deleted flag

Also refactored File class to use a boolean for this flag.

Target: trunk
Require-notes: no
Require-book: no
spacemanager: Remove empty expired or released reservations

There is no point in keeping an empty reservation that has expired or has
been released.

Target: trunk
Require-notes: yes
Require-book: yes
spacemanager: Don't accept output retention policy

Since we dont' implement output in dCache, there is no
point in allowing such reservations to be created.

Target: trunk
Require-notes: no
Require-book: no
spacemanager: Fix help output of reserve space

@Argument help is currently not rendered as part of the help
output. This patch moves the mentioning of the optional suffix
to the main description.

Target: trunk
Require-notes: no
Require-book: no
spacemanager: Minor UI improvements

Target: trunk
Require-notes: no
Require-book: no