Create OSC loadbalancer show command

[Michael Johnson]

We need to implement the "openstack loadbalancer show" command in the OpenStack client plugin.

It should support the following options:

usage: openstack loadbalancer show [-h] [-f {json,shell,table,value,yaml}] [-c COLUMN]
                           [--max-width <integer>] [--print-empty]
                           [--noindent] [--prefix PREFIX]
                           <lb-id>

Display load balancer details

positional arguments:
  <lb-id> Load balancer to display (name or ID)

optional arguments:
  -h, --help show this help message and exit

output formatters:
  output formatter options

  -f {json,shell,table,value,yaml}, --format {json,shell,table,value,yaml}
                        the output format, defaults to table
  -c COLUMN, --column COLUMN
                        specify the column(s) to include, can be repeated

table formatter:
  --max-width <integer>
                        Maximum display width, <1 to disable. You can also use
                        the CLIFF_MAX_TERM_WIDTH environment variable, but the
                        parameter takes precedence.
  --print-empty Print empty table if there is no data to show.

json formatter:
  --noindent whether to disable indenting the JSON

shell formatter:
  a format a UNIX shell can parse (variable="value")

  --prefix PREFIX add a prefix to all variable names

Fields:

   - admin_state_up
   - created_at
   - description
   - flavor
   - id
   - listeners
   - name
   - operating_status
   - pools
   - project_id
   - provider
   - provisioning_status
   - vip_address
   - vip_network_id
   - vip_port_id
   - vip_subnet_id

Note: provider and flavor are not implemented in the API yet.