Patch objpool.http to support SSL Authentication

Refs #54

The module objpool.http provides pooled connections without SSL
Authentication.
A new connection class is implemented in kamaki.clients.utils.https
The name of the class is HTTPSClientAuthConnection
The module objpool.http is patched by kamaki so that instances of
PooledHTTPConnection can provide HTTPSClientAuthConnection instances
as https connections.

Also, astakosclient is patched to use the same connection class in
case of an https connection.
Add ignore-ssl and ca-certs options to CLI

Fixes #54

Both options are set either in the config file or as runtime
arguments.

ignore-ssl option allows connections without checking SSL
certificates

The ca-certs option provides a CA file for SSL authentication

These options are mutually exclussive

The default behavior is to raise SSL errors if no cert files are
provided

In case of an SSL error, kamaki stops and notifies the user
except if they use the ignore-ssl option