mon: OSDMonitor: split 'osd pool set' out of 'prepare_command'

We should start doing this across the whole 'prepare_command' function.
Makes it prettier to the reader, and easier to add new code.

Signed-off-by: Joao Eduardo Luis <joao.luis@inktank.com>
mon: OSDMonitor: allow (un)setting 'hashpspool' flag via 'osd pool set'

Signed-off-by: Joao Eduardo Luis <joao.luis@inktank.com>
osd: osd_types: Output pool's flag names during dump

Signed-off-by: Joao Eduardo Luis <joao.luis@inktank.com>
mon: MonCommand: make 'osd pool set' accept a String instead

We need to pass 'true' or 'false' for flag 'hashpspools' -- we now deal
with the int or string part of the foo in mon/OSDMonitor.cc. :)

Signed-off-by: Joao Eduardo Luis <joao.luis@inktank.com>