In ropenscilabs/vcr: Record 'HTTP' Calls to Disk

vcr: the name comes from the idea that we want to record something and play it back later, like a vcr
cassette: A thing to record HTTP interactions to. Right now the only option is the file system (writing to files), but in the future could be other things, e.g. a key-value store like Redis
fixture: A fixture is something used to consistently test a piece of software. In this case, a cassette (just defined above) is a fixture - used in unit tests. If you use our setup function vcr_setup() the default directory created to hold cassettes is called fixtures/ as a signal as to what the folder contains.
Persisters: how to save requests - currently only option is the file system
serialize: translating data into a format that can be stored; here, translate HTTP request and response data into a representation on disk to read back later
Serializers: how to serialize the HTTP response - currently only option is YAML; other options in the future could include e.g. JSON
insert cassette: create a cassette (all HTTP interactions will be recorded to this cassette)
eject cassette: eject the cassette (no longer recording to that cassette)
replay: refers to using a cached result of an http request that was recorded earlier