installer does not work when behind a proxy

[larsnystrom]

As @rbywater pointed out in the pull request that introduced this bug (#141), the installer script no longer works if you have both http_proxy and no_proxy set in your environment.

If your no_proxy setting does not contain getcomposer.org, then $this->rulePort will be null (or actually not set at all), which will cause NoProxyPattern::test() to always return true.

The simplest fix I can think of would be to just return false when there is no rulePort set, since that means that getcomposer.org could not be found in the no_proxy var. That would also make sense given the methods docblock:

Returns true if NO_PROXY contains getcomposer.org

Edit: Just noticed that there is already a pull request to fix this: #143