v1.5

Uses the new request.Context from Go 1.7 for Go 1.7 automatically. Note that gorilla/context is incompatible with Go 1.7.

6958173 [doc] Fixed readme mux path prefix (#51)
10e8fd1 [docs] Fix a few minor typos in examples. (#54)
fdae182 docs: fix minor typo (#50)
7f54448 [docs] Fix incorrect function name in docs (#49)
bbe6687 [docs] Fix syntax typo (#48)
0ff6a2c [docs] Improve commented code (#46)
a8abe8a [docs] Mentions passing csrf.Secure(false) in local dev environments.
a9c30ae [bugfix] Remove dependency on gorilla/context for go1.7+ (#42)
4642ecf [bugfix] Support a cookie MaxAge of 0. (#39)
101aaa4 Merge branch 'master' of github.com:gorilla/csrf
2a06c32 [ci] Add 1.6; skip install block; don't simplify.
0bb4971 [deps] Move from errors -> github.com/pkg/errors
dd1bce8 [deps] Move from errors -> github.com/pkg/errors