Add support for secretary exec -- cmd [args..] which will decrypt all environment variables and all command line arguments without requiring an embedding shell to do the work.

• Now builds binary using Go v1.9.2

• Added version command (#18)

• Updated AWS SDK to v1.6.18 to solve #16 (#17)

• Use EC2 meta-data service to autodetect AWS region if needed (#14)
• Enable Shared Config to support $AWS_DEFAULT_REGION (#14)

• Enable the use of environment variables for TLS (#11)

• Support TLS end-to-end encryption for Secretary daemon (#10)

• Check that environment variables are valid identifiers when using encrypted strings (#8)
• Upgrade to Go 1.6 (#9)

• Adds /v1/status endpoint (#7)

• Enables encryption and decryption using AWS Key Management Service. (#6)