Adding gamair data

[IlanReinstein]

I would like to add the datasets from Simon Wood's book on GAM's using R.

I've already used Vincent's (Rdatasets) package to create documentation and have the files locally ready to add.

[IlanReinstein]

Submitted PR #103

[tlienart]

Hello @IlanReinstein this is now merged (finally), though it breaks some test in terms of documented datasets:

RDatasets.jl/test/datasets.jl

Lines 13 to 14 in 73f96a0

	@test_broken size(dfs_found, 1) == size(dfs_documented, 1)
	@test_broken sort(dfs_documented[!, [:Package, :Dataset]]) == sort(dfs_found)

would you be willing to look into this?

(sorry I'm not a main maintainer so trying to figure things out along the way...)