virt: fix libvirt_xml, virsh, utils_misc & friends

+ libvirt_xml:
    + Improved docstring
    + Removed uuid module usage
    + Removed duplicate method definitions
    + Fixed comment spelling mistakes
    + Added os_arch_machine_map property to LibvirtXML

+ utils_misc:
    + Remove unused Closure Class
    + Fixed indentation / spacing
    + Added comments

+ utils_misc unittest:
    + Cleaned up nested class/method definitions
    + Unfolded some complex assignments
    + Fixed indentation / spacing
    + Add some dict-method unittests

+ virsh:
    + Updated/Clarified module docstring
    + Removed unnecessary DaArgMangler class
    + Fixed specialized VirshClosure Class
    + Cleaned up VIRSH_EXEC usage & warning
    + Replaced old use of PROPERTIES with __slots__ (resolved TODO)
    + Enforced setting of 'uri' and 'virsh_exec' properties
    + Made VirshSession class record the uri for later comparison
    + Major VirshPersistant cleanup/bugfix
        + Added session acounting (helps unittests)
        + Added close_session method to unify behavior
        + Fixed new_session to properly close alive existing sessions
        + Fixed set_uri to open new session only on uri change WRT old session
        + Cleaned up virsh.command to work with VirshPersistant properly

+ virsh_unittest:
    + Added back unittest module (some tests ignored if no libvirt)
    + Added 8 tests for VirshClosure
    + Added VirshPersistent session count check to ConstructorsTest
    + Added help command cache tests
    + Added VirshPersistant test teardown double-check session accounting

+ libvirt_vm: Cleaned up hvm/pvm arch and machine-type detection/check

+ guest-os.cfg.sample:
    + Added vm_arch_name param for every OS defaulting uname -m
    + Removed a few guest os types that aren't used anymore
Signed-off-by: NChris Evich <cevich@redhat.com>