Adds separate variables for configuring Nitro task thread pools.

Replaces `bbc.nitro.threadCount` environment variable with
`bbc.nitro.threadCount.today` and `bbc.nitro.threadCount.fortnight`
variables which define the thread counts for the today-only and
fortnight nitro update task pools.
Introduce environment variable controlling page size of nitro requests

Add `bbc.nitro.requestPageSize` variable, defaults to 300.
Add request logging for Nitro V1 client
use glycerin 0.1.6
add nitro root resource env