BasicManagement: handle argument errors consistently

Return Error_Other if the arguments are not within implementation
specific limits. Test initialization is no longer handled by specific
init() function: instead the tests constructed() checks argument
values and sets a enum InitState to proper value.

The InitState enum exists so that ExecutionState could map 1:1 to the
UPnP state variable without ugly hacks.

This approach is simpler for BasicManagement (one less method call) and
produces arguably better results: at least the caller of the UPnP api
now gets meaningful error messages.
BasicManagement Ping: simplify state handling

The base class will normally handle execution state: setting it to
complete can be used to skip iterations but Ping does not need that.
BasicManagement NSLookup: handle default repetition and timeout values

add property setters for repetition and timeout, so the default values
can be used for value '0'. repetitions still uses base class 'iterations'
variable internally.

Rename variables in BasicaManagement to be clearer.
Merge pull request #10 from jku/wip-errors

Handle UPnP argument limits consistently