TLS options doesn't work with custom agent in Node.js < 0.12

[narqo]

WIP! Waiting for tests!

• fix #119
• closes #86

Node.js<0.12 creates a new Agent for https request if tls options are passed.

If user specifies her custom agent (or agent properties in our case), this agent should deal with TLS options by itself.

This patch is only necessary for Node.js=0.10 but should not affect modern versions.

› ~/.local/opt/node-v0.10/bin/node -e "require('./')({ protocol:'https:', /*···*/ ca: require('fs').readFileSync('./MyInternalRootCA.pem') }, function(err, res) { console.error(err); console.log(res ? res.statusCode : '?') })"
null
200

› ~/.local/opt/node-v0.12/bin/node -e "require('./')({ protocol:'https:', /*···*/ ca: require('fs').readFileSync('./MyInternalRootCA.pem') }, function(err, res) { console.error(err); console.log(res ? res.statusCode : '?') })"
null
200

› ~/.local/opt/node-v4/bin/node -e "require('./')({ protocol:'https:', /*···*/ ca: require('fs').readFileSync('./MyInternalRootCA.pem') }, function(err, res) { console.error(err); console.log(res ? res.statusCode : '?') })"
null
200

› ~/.local/opt/node-v0.10/bin/node -e "require('./')({ protocol:'https:', /*···*/ rejectUnauthorized: false }, function(err, res) { console.error(err); console.log(res ? res.statusCode : '?') })"
null
200

[narqo]

:dancer:

[Flackus]

:8ball: