Thanks to otakup0pe, nicr9, marcoslopes, caiotomazelli,
and blarghmatey for their contributions!
IMPROVEMENTS:
* Add EC2 auth support [GH-61]
* Add support for token accessors [GH-69]
* Add support for response wrapping [GH-70]
* Add AppRole auth support [GH-77]
BUG FIXES:
* Fix `no_default_policy` parameter in `create_token` [GH-65]
* Fix EC2 auth double JSON parsing [GH-76]