"slcli firewall cancle" failed

[MarikoTagawa]

Please triple-check to make sure that you have properly masked out user credentials like usernames, passwords and API keys before submitting your issue

Expected Behavior

Cancel the specified firewall

Actual Behavior

Got the following error and failed.

$ slcli firewall cancel "vlan:8003"
This action will cancel a firewall from your account. Continue? [y/N]: y
An unexpected error has occured:
Traceback (most recent call last):
File "/Library/Python/2.7/site-packages/SoftLayer-5.2.0-py2.7.egg/SoftLayer/CLI/core.py", line 163, in main
cli.main(**kwargs)
File "/Library/Python/2.7/site-packages/click/core.py", line 680, in main
rv = self.invoke(ctx)
File "/Library/Python/2.7/site-packages/click/core.py", line 1027, in invoke
return _process_result(sub_ctx.command.invoke(sub_ctx))
File "/Library/Python/2.7/site-packages/click/core.py", line 1027, in invoke
return _process_result(sub_ctx.command.invoke(sub_ctx))
File "/Library/Python/2.7/site-packages/click/core.py", line 873, in invoke
return ctx.invoke(self.callback, **ctx.params)
File "/Library/Python/2.7/site-packages/click/core.py", line 508, in invoke
return callback(*args, **kwargs)
File "/Library/Python/2.7/site-packages/click/decorators.py", line 63, in new_func
return ctx.invoke(f, obj, *args[1:], **kwargs)
File "/Library/Python/2.7/site-packages/click/core.py", line 508, in invoke
return callback(*args, **kwargs)
File "/Library/Python/2.7/site-packages/SoftLayer-5.2.0-py2.7.egg/SoftLayer/CLI/firewall/cancel.py", line 30, in cli
mgr.cancel_firewall(firewall_id, dedicated=True)
File "/Library/Python/2.7/site-packages/SoftLayer-5.2.0-py2.7.egg/SoftLayer/managers/firewall.py", line 90, in cancel_firewall
billing_id = fwl_billing['billingItem']['id']
KeyError: 'billingItem'

Feel free to report this error as it is likely a bug:
https://github.com/softlayer/softlayer-python/issues

Environment Information

Operating System: Mac OS X 10.12.3
softlayer-python version (slcli --version): slcli (SoftLayer Command-line), version 5.2.0

[camporter]

I've made a PR to fix the issue of the unexpected error when billing is not available for a firewall.

[allmightyspiff]

I've merged the changes into the master branch, and this fix will be in the 5.2.8 release.