* Improve specs and docs

* Several bugfixes
* Support for dynamic creation of pools and more configuration options.
* Add support for connect_options
    * Enables the user to pass socket options, for instance ip and port,
      that will be used when connecting the socket
    * Allows the user to specify SSL options during the connect phase
* Add support for "streaming" of entities
* Add start/0 and stop/0
* Fix for unexpected messages after request has been completed
    * When the client process is trapping exits (which some eunit versions seem
      to be doing by default) there would be {'EXIT', Pid, normal} messages left
      after completing requests which came from the lhttpc_client process.
      These are now avoided.
* Add rebar support (thanks to Benoit Chesneau)
* Add support for HTTP basic auth (Filipe Manana)
* Add support for IPv6 (Filipe Manana)
* Several URL parsing fixes (Filipe Manana)
* Add support for proxies via HTTP CONNECT method (Filipe Manana)
* Add connection limit to the connection pool (Filipe Manana)
* Add suport for using multiple connection pools - different requests can now
  use different connection pools (Filipe Manana)

maintenance