Set default logger to astakosclient.AstakosClient

Fixes grnet/kamaki#58

This bug fix refers to the LoggedAstakosClient wrapper.
The class AstakosClient is not forced to use a default logger.
Show the correct name when switching kamaki users

Fixes grnet/kamaki#66
Restore compatibility with Python 2.6 in HTTPS cls

Fixes grnet/kamaki#73

The problem is caused by the argument "source_address' when
instantiating "httplib.HTTPSConnection" in "kamaki.clients.utils.https"
This argument was added in Python 2.7, therefore a TypeError would
ensue with Python 2.6
This is fixed by catching the TypeError and retrying without the
"source_address" argument.
Fix Python 2.6 compatibility with string "encode"

String method "encode" accepts named arguments only since Python 2.7
Rename "raise_ssl_errors" to "insecure"

Refs grnet/kamaki#74

The modified flag is located in in HTTPSClientAuthConnection of
"kamaki.clients.utils.https".
The default flag value is reversed.

Also, rename the method "patch_to_raise_ssl_errors" to "patsh_use_ssl".
The boolean values passed to this method remain the same.

Update documentation accordingly.