Make helper functions & config for Kaltura player URLs

[mberkowski]

1. Let's make Kaltura players configurable, maybe in an initializer that sets a config value for the account id 1369852, and for embed player IDs we will need like uiconf_id = 54071352, with a separate value for audio, video, etc.

2. Then let's make helper functions to avoid building out Kaltura embed urls directly in views and returns one built out of

https://cdnapisec.kaltura.com/p/#{accountid from config}/embedPlaykitJs/uiconf_id/#{player ui for current context}?iframeembed=true&entry_id=#{media ID}"