Multiple selectors

[timfallmk]

Closes #216

The only problem is that this changes the config file format, which cases Viper to barf on validation if it detects the old format. Should we add some sort of conversion here? @grampelberg

Updating Old Config Files:
This update introduces a slight change to the config file schema that allows use of multiple selectors (tags) when specifying a spec. Specs created prior to this version are not compatible and must be updated.

There are two options for updating configs:

1. Delete and recreate the specs
2. Update the selectors field

For option 2, you'll need to do the following:

The old config format specified a single key-value pair for configs, like so:

spec:
- name: intent-lacewing
  containername: ""
  pod: ""
  selector: app=test
  namespace: default

The new config format changes the selector value to a map, allowing more than one selector to be specified:

spec:
- name: intent-lacewing
  containername: ""
  pod: ""
  selector: 
  - app=test
  - tier=backend
  namespace: default

Change this field to a map with the appropriate values and it should validate correctly. You will need to reload kysnc watch to validate the new config.

When (re)creating specs, selectors can be passed in as comma-separated values --selector=app=test,tier=backend or as multiple flags -l app=test -l tier=backend.

[grampelberg]

@timfallmk how about throwing a friendly error in and bumping the major version?

[timfallmk]

@grampelberg I'll add the config "update" steps to the PR and Release Notes. This is ready for merging.