ENH: updated https and agent option

Removed logic from createProxyServer and put it into setupOutgoing.

Conflicts:
	lib/caronte.js
ENH: added new https example, needs to be simplified before merge
updated existing example with log output
ENH: added 'headers' to available options, to add or overwrite existing headers
ENH: updated example
Merge branch 'agent' into caronte
ENH: updated examples
ENH: updated agent options in `common.setupOutgoing`
DOC: updated readme with options
FIX: tests. still need to add more tests tho
TEST: added agent and header tests
DOC: updated readme

@yawnt I think it is good to go. If you have any other tests in mind let me know.
Merge pull request #482 from srossross/caronte

[merge] https & agent