vos should honor maxquota argument or return error

Invoke vos as follows:

vos create someserver a somevolumename 5000000000

Vos will create a volume with some arbitrary maxquota
and return success. In case of an overflow vos should
either

	* not create the volume and return an error

	* create the volume with maximal possible 
	  quota and issue a warning to the user

What maxquota the volume actually gets in the example above is left as
an exercise for the curious, but is not 5TB. (I'm only a proxy for
this error report) and differs between OpenAFS and Arla I'm told.

Harald.