Support Connector without DNS

[clue]

• Split Connector into TcpConnector and DnsConnector
• Legacy Connector now acts as a proxy for BC only

This PR builds on top of #43, so the diff also includes its changes. Look here for changes only related to this PR alone. (no longer applies after rebasing)

Fixes#12
Supersedes/closes#7

[clue]

I consider this feature complete, though this is probably blocked until #43 is merged. As such, I've marked this WIP for now.

Any feedback is welcome! Perhaps this PR also helps to emphasize my motivation for the API used in #43/#45.

[clue]

I've just updated this PR so that it no longer includes a BC break.

[clue]

I've just rebased this on the current master now that #43 is in.

Ready for review :) Ping @WyriHaximus, @cboden

[WyriHaximus]

LGTM, this is a very welcome feature 👍

[clue]

I've just updated this PR so that it no longer includes a BC break.

This currently does not break compatibility what's been documented in our README, however the public interface of the Connector class had to be changed. Should we consider this a BC break, i.e. should this be v0.4.5 or v0.5.0?

[WyriHaximus]

We might want to consider this a BC break as the publicly exposed API has changed. Also there are a ton of packages uses the class: http://packanalyst.com/class?q=React%5CSocketClient%5CConnector

[clue]

We might want to consider this a BC break as the publicly exposed API has changed. Also there are a ton of packages uses the class:

For the reference, not a single one of the examples instantiating the Connector and calling its create() method is affected.

Only the two classes that extend the Connector and access its protected members would be affected.

I agree that we might want to play safe here and consider this a BC break nonetheless. The CHANGELOG should include some details that this doesn't affect most users though.

Also, I've just marked the internal APIs as such, so this doesn't happen again if we change the internal APIs.

? :)

[jsor]

Typo: connection -> Connection

[clue]

Thanks for spotting, fixed! :)

For the reference: This code has been like this ever since the very first commit in this repo.

[jsor]

A small typo, otherwise LGTM

[WyriHaximus]

LGTM