Add support for token-based authentication

Changelog for v0.1.0:

• PR #1 Add support for token-based authentication by @welteki

Commits
4960a69 Add usage examples to README by @welteki
02a8d16 Support multiple authentication methods by @welteki

Changes: v0.0.2...v0.1.0

Generated by Derek

Add info endpoint

Changelog for v0.0.2:

Commits
8c6903c Add Info endpoint by @alexellis
4b4ac8d Add Deploy and GetFunction methods by @alexellis

Changes: v0.0.1...v0.0.2

Generated by Derek

Initial release

Changelog for v0.0.1:

Commits
8fb2ba3 Initial by @alexellis
b2a4c4f Initial commit by @alexellis

Changes: https://github.com/openfaas/go-sdk/commits/v0.0.1

Generated by Derek