Totally restructure the lhttpc client. lhttpc_client is now a gen_server.

Now it supports conections without using a pool.
It is possible to define clients and use them to establish connections.
All the code from this commit was done by me and Diana Corbacho.
Remove lhttpc_manager from supervisor init(). Fix bug in ensure_call function.

Before one pool called lhttpc_manager was created during initialzation. With the new redesign this is not necessary.
Improve format, remove comented lines and add doc to some functions.
Fix error to allow to specify only a patch when calling request_client.

Before it used to crash due to a call to parse_url.
Fix client reconnect problem when server returns headers to close connection.

It was not able to reconect once the server replied with a connection close header. Now it reconnects to the same host specified when the user starts the client using lhttp:connect_client() function.
Change response format from Reply to {ok, Reply}.

Made several tests fail and other clients reply with the new format.
Do not close the socket in terminate if it is undefined. (it was already closed). Fix one test case.
Fix some test cases.
Fix connect functionality and attempts to reconnect
Fix typo error in call parameters
Refactor test code to reuse in other suites
Fix some issues related with read body part functions.

Test cases that do not pass at the moment are also commented.
Merge remote-tracking branch 'ramon/new_version' into new_version
Fix get_body_parts size control for fixed length bodies
Fix get body parts for fixed length messages and some parameters configuration

* upload_window is not used any more, the gen_server synchronous call regulate the flow
* pool options are a grouped argument in connect call
Fix error related with connection_close test. (exception made gen_server crash).
Remove message_queue test. Uncomment tests that already pass.

Also remove some lines of old commented code.
Fix error related with suspende_manager test case (timeout when connecting client).
Fix errors found by dialyzer. Now dialyzer test pass without problems.

Still migth be necessary to improve the specs.
Fix partial upload/download