impr: add ca-central-1 region
impr: add ca-central-1 region

Add `ca-central-1` region to represent the new Canada Central 1 AWS region.

Closes #470.

ford-prefect/rusoto,DualSpark/rusoto,rusoto/rusoto,cmsd2/rusoto,SecurityInsanity/rusoto,noggleboggle/rusoto,mattico/rusoto,DualSpark/rust-aws,ford-prefect/rusoto,DualSpark/rusoto,rusoto/rusoto,mattico/rusoto,mthjones/rusoto,mthjones/rusoto,mattico/rusoto,DualSpark/rust-aws,SecurityInsanity/rusoto,DualSpark/rusoto,rusoto/rusoto,DualSpark/rust-aws