Add option to set $http config params in config.js

To get puppetexplorer to work with a SSO secured PuppetDB API directly,
beside seting up CORS, we need to set withCredentials to true. This
allows the browser to include login cookies in the api requests.
Add a option to specify the api version to use.
Allow puppetexplorer to cope with {,cert}name

This allows puppetexplorer to cope this the name vs. cername
inconsistancy in the nodes api endpoint.
Fix catalog_timestamp attribute name.