Add support for the scanning API (#74)

* Refactor secure and monitor into it's own files
_client.py has grown too big. Moving SdcMonitor and SdcSecure into
separated files.

* Fix python style (pep8)
Make the code pep8 compilant except for line lenght (E501) and for
comparisons to none (E711) and bool (E712) using '==' or '!='.

* Add SdScanningClient class with the secure scanning API
Add image, registries and subscription support. Importing some anchore
helper functions from anchore-cli into sdcclient/_anchore.

* Add support for scanning policies

* Add support for scanning alerts and runtime

Author: meskio

sdcclient/__init__.py

@@ -1,3 +1,4 @@
-from sdcclient._client import SdcClient
-from sdcclient._client import SdMonitorClient
-from sdcclient._client import SdSecureClient
+from sdcclient._monitor import SdcClient
+from sdcclient._monitor import SdMonitorClient
+from sdcclient._secure import SdSecureClient
+from sdcclient._scanning import SdScanningClient