Fix the subnet dhcp enable/disable param

neutron subnet-create/update use --enable-dhcp and --disable-dhcp
to manage the dhcp of the subnet

Change-Id: I4c19a770adba2c9eb601e4f389964d3da49cc93e
Merge "Fix the subnet dhcp enable/disable param"
Unescape value in parse_allocation_pool

Neutron in Fedora 21 changed library for formating shell output and
it's now escaped. We just make sure we'll unescape it before applying
regexp.

Change-Id: I56f1f05576fe4d2dde5d1d59184b03d0ad244783