added NAMESPACE property to end-point commands

Associated functions are now invoked with a namespace object as a first
argument rather than connection. Default namespace is root/cimv2. To
change it, one can define command with:

class ListClassFromOtherNamespace(LmiLister):
    NAMESPACE = 'other/namespace'
    ...

To preserve the previous behaviour (pass the connection object again),
NAMESPACE needs to be set to False.
added changelog
changed license to 2-clause BSD

Changed header of all source file to contain Simplified BSD License
instead of LGPLv2.1+.
doc strings updates

spaces, be gone