Implement unit tests for kamaki.clients.astakos

Old unitests were testing the old AstakosClient class, which
is not been used anymore. The new package inctroduces wrapper
classes for the synnefo.AstakosClient class. The later is not
tested in this patch, but the wrapper classes and kamaki-specific
extentions are.
Fix minor errors in CycladesClient unit test
Update kamaki.clients.pithos unit tests
Fix errors in unit tests of "kamaki.cli.*"

Refs #18

Most errors are caused by changes in the names of classes,
methods and packages.
Remove test of deprec. method "_raise_for_status"
Avoid false alarm when testing kamaki threads

The false alarm in caused when testing kamaki threads that run too
fast to catch them in an unfinished state. The "assert thread as
unfinished" check fails in that case, although nothing is wrong
with the functionality.