Make package skeleton

[raymondben]

NBN4R (https://github.com/BiologicalRecordsCentre/NBN4R) is a wrapper package around ALA4R. It changes the server URL addresses and other ALA-specific settings (see onload.R) and creates cosmetic re-naming of ALA functions so that they appear as NBN-named functions.
We should make a skeleton package like this so that other national installations that want their own R package can use it as a starting point.

See also #29

[raymondben]

Guesstimated time - 2 days to take NBN4R and strip it back to a skeleton. Another 5 days to document the process of writing a new package based on that skeleton.