Add version to command line and user agent string

[jimisola]

PR will:

• add -V/--version to command line: Add version cmd line option (-V, --version) #30
• add version to user agent string: get version from something and apply into user agent-string #25

[hamnis]

Thanks. :)

[hamnis]

@jimisola you need a new relase with this?

[jimisola]

No stress on my behalf. Did you test it?
Would have liked to write some automated tests but.. I did some manual tests though, but nice to know that someone else tried it.

[jimisola]

@hamnis Any chance of making a new release?