Fixes unit tests under go 1.16, fix for UTC timestamp parsing, adds go modules support

[dimalinux]

Unit test fixes

The unit tests, at least under go 1.16, were failing:

panic: x509: certificate relies on legacy Common Name field, use SANs or temporarily enable Common Name matching with GODEBUG=x509ignoreCN=0

I put in new certificates, separating the client from the server certificate. The server certificate now has a subject alternative name section which includes both localhost and 127.0.0.1.

Timestamp parsing fixes

RFC 3339 timestamps do not have a fixed size length, but they also do not contain any spaces: https://tools.ietf.org/html/rfc3339#section-5.8

I changed the code to terminate after the first space instead using the size of the formatting string to fix the issue.

Go modules support

Added go modules support.

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