Basic support for slugs, names and labels in group_by and host_vars

[rthomson]

Implements a very simple method for using slug, name and label fields from netbox API for group_by or host_vars as discussed in #4 and #22.

This is not likely to be the "best" approach as it requires authors of the netbox.yml configuration file to know which fields they want to group_by or use for host_vars are of which type.

This should be backwards compatible with existing YAML configurations.

[rthomson]

Here's an example netbox.yml configuration using names, slugs and labels:

netbox:
    main:
        api_url: 'https://localhost/api/virtualization/virtual-machines/'
        api_token: '1234567890'

    group_by:
        names:
            - cluster
        slugs:
            - platform
        custom:
            - ansible_groups

    hosts_vars:
        ip:
            netbox_primary_ip: primary_ip
            ansible_host: primary_ip
        names:
            netbox_cluster: cluster
            netbox_vcpus: vcpus
            netbox_memory: memory
            netbox_disk: disk
            netbox_tenant: tenant
        slugs:
            netbox_role: role
            netbox_platform: platform
        labels:
            netbox_status: status
        custom:
            ansible_user: ansible_user
            ansible_port: ansible_port
            netbox_ansible_configure: ansible_configure

[coveralls]

Coverage remained the same at 100.0% when pulling 3d551e9 on rthomson:slugs-names-labels into b5e053d on AAbouZaid:devel.

[coveralls]

Coverage remained the same at 100.0% when pulling 3d551e9 on rthomson:slugs-names-labels into b5e053d on AAbouZaid:devel.

[Keyhaku]

Hello,

I think there is a little error in labels key map,

 self.key_map = {
...
     "labels": "value",

shouldn't it be ?

 self.key_map = {
...
     "labels": "label",

If I'm correct, this should fix #17