Content Views - initial support for filters

Initial support includes:
- create, remove, update, delete of filters

During create/update, the parameters will be passed by providing
a file that contains json format.  In the future, we'll also add
ability to specify them via the CLI.

The following is an example of a json file for a pkg filter:
```
{
  "units":[
    {
      "name":"zip",
      "version":"10.0",
      "inclusion":"true"
    },
    {
      "name":"zap",
      "version":"1.0",
      "inclusion":"false"
    }
  ]
}
```