kohabug 1993 - task scheduler improvements

kohabug 1993 - task scheduler improvements

[1] Removed hardcoded path to original developer's
    Koha configuration file; now checks KOHA_CONF.
[2] Now attempts to figure out if a task was successfully
    added to the task queue; if it wasn't, the failure
    is now reported in the  task scheduler page.
[3] When traveling to the task scheduler page from a
    saved report, the report in question is now
    selected by default.
[4] Removed the button to edit a queued task; this is
    not supported.

This patch is essentially a bandage; I've added a BUGS
section and some FIXMEs to the POD for C4::Scheduler
detailing some issues - a refactoring of the task
scheduler is in order at some point.

Signed-off-by: Joshua Ferraro <jmf@liblime.com>