TrimSpace from string fingerprint before hex.DecodeString

[jspraul]

Rookie passing "-bsau [string fingerprint]" as one parameter when debugging. getopt still worked but didn't trim the leading space from string fingerprint.

The end of email parsing at

smimesign/parse_user_id.go

Line 106 in 3564e86

name = strings.TrimSpace(id[n.start:n.end])

calls TrimSpaces everywhere so I thought it might be worth doing the same defensively for the string fingerprint.

PS. Both my 👍 👍 's up for pull cgo windows to syscall #93 and @tg123, it's the only reason I'm here.

[jspraul]

Sorry, requiring all commits to be signed wasn't mentioned in CONTRIBUTING.md, but it makes sense.

If there's any interest in this at all (very minor issue and tiny fix) I can go through this again, signing commits this time.