[hostBasedConfig] implement way to speficy proxy host based config

[spalger]

Fixes #69

This PR adds a way to specify configuration that is host based. It does this by adding a new config key, sense.proxyConfig. The value of this key is an array of objects, each of which is a rule that may change the configuration for a request by matching it's url.

sense.proxyConfig[].match

Each rule in the proxyConfig list may define a match property which contains a set of wildcard patterns to be matched against incoming requests. This match object can contain the following properties, they all default to *:

name	purpose	example input
match.protocol	match the protocol of the request	https
match.host	match the hostname of a request	*, *.internal.org
match.port	match the port, is empty when no port in the request	92?? (9200-9299)
match.path	match the path, does not include the query string	/.kibana/**

sense.proxyConfig[].ssl

Each rule can specify ssl configuration to be applied to matching requests. The ssl object can contain the following properties:

name	purpose	default
ssl.verify	If set to false then invalid ssl certificates will be allows for this request. This setting has not effect if ssl.ca, ssl.cert, or ssl.key are defined	true
ssl.ca	A certificate authority that will be used to verify the certificate of the server
ssl.cert	A certificate which should match that of the server
ssl.ca	A private key... I think this decrypts the ssl.cert but I'm not sure

sense.proxyConfig[].timeout

The only non-ssl-related config that can be set via sense.proxyConfig is timeout. Setting this will change the timeout applied to this request.

Example

sense:
  proxyConfig:
    - match:
        host: *.internal.org
        port: 92??
      ssl.ca: /opt/certs/internal.ca

    - match.host: *
      ssl.verify: false
      timeout: 180000 # 3 minutes

Creates the following configs:

=> request: http://es.internal.org:9200
<= config:
        ssl.ca: /opt/certs/internal.ca
        timeout: 180000

=> request: http://myfoundcluster.found.no:1234`
<= config:
        ssl.verify: false
        timeout: 180000

---

Remaining Work:

• convert host matching to globs, the RegExp syntax is confusing
• tests

[spalger]

Backported to 4.x and 4.4