Adding preliminary models for rest of asset types

Gemfile

lib/liudesk_cmdb/models/generic.rb

lib/liudesk_cmdb/models/generic/client.rb

lib/liudesk_cmdb/models/linux_client.rb

lib/liudesk_cmdb/models/linux_computerlab.rb

lib/liudesk_cmdb/models/mac_client.rb

lib/liudesk_cmdb/models/windows_client.rb

lib/liudesk_cmdb/models/windows_computerlab.rb

test/fixtures/get_linuxclient.json

test/test_helper.rb

test/test_v1_models.rb