Path options for TLS cert added

[kvokka]

When I've tried to use https://github.com/NARKOZ/gitlab gem, I needed to serialize TLS options to global variable. It is very ugly, so, I added _path option for p12 and pem for key and password files, so, user may store it in options directly, or use path. Syntax will be like { pem_path: '/path/to/cert'}

I hope you'll like it

[kvokka]

gitlab gem will support this, if you only merge PR, or, say please, what you dislike please. Thank you

[jnunemaker]

Closing as stale.