sliverstatus prevents deletesliver for sliver which has failed at createsliver time

[lnevers@bbn.com]

According to Ilia:

When a slivercreation fails there is garbage collection that must occur before the sliver name can be re-used. An experimenter can deletesliver to force the cleanup and thus be able to re-use the sliver name again.

Two scenarios have been tested which found conflicting results:

Scenario1:

1. create slice - OK
2. create sliver w/bad rspec, which causes expected failure - OK
3. delete sliver - OK
4. re-create the same sliver again with corrected rspec - OK

Scenario2:

1. create slice - OK
2. create sliver w/bad rspec, which causes expected failure - OK

3. sliverstatus reports "Other Exception: java.lang.NullPointerException?" - Maybe ok?
4. Delete sliver fails with "(got result 'False'). (no reason given) " - Can no longer delete the sliver

[ahelsing@bbn.com]

See related ticket #156