Added P4#run_shelve and P4#delete_shelve as special cases - similar to P4Python.
P4#run_shelve allows passing in of a hash, assumed to be a changelist (i.e
shelvelist) spec, similar to P4#run_submit.
P4#delete_shelve adds an extra "-c" to the arguments before the shelve list number
if "-c" is not already in the argument list.
User-visible changes to be documented in the release notes.