fix for status without report timestamp

nodes without a report timestamp will status unreported

pep8 fix
Merge pull request #19 from juliushaertl/feature-nodestatus

fix for status without report timestamp
api: Fix too much copy-paste.
check for key 'status' in node dictionary
use "node['status'] = None" as default
Merge pull request #20 from fretterick/fix-nodes_with_status

Make sure the status key actually exists on a node.
pypuppetdb/api/v3.py: Trivial docs fix
Merge pull request #21 from nibalizer/doc_fix

pypuppetdb/api/v3.py: Trivial docs fix