Support --force for pool disabling

Lets us do the three way button for disabling a pool member:

* `f5 pool enable` Enabled (All traffic allowed)
* `f5 pool disable` Disabled (Only persistent or active connections allowed)
* `f5 pool disable --force` Forced Offline (Only active connections allowed)

Also fixed a bug where Array(a hash) returns an array of arrays instead
of an array of hashes when looking at a pool containing only one member