Fix capitalization of Baudrate in [DeviceComissioning] section.

As pointed out in #452, there is an inconsistency in the CiA 306 spec
regarding the exact spelling.  Under DeviceComissioning (sic!), it is
spelled with a lowercase "r", while under DeviceInfo it is BaudRate_*
with an uppercase "R".

That change however broke the tests, because the library currently
handles keys in a case-sensitive way (which is wrong in itself).

test/sample.eds

@@ -32,7 +32,7 @@ LSS_Supported=0
 [DeviceComissioning]
 NodeID=2
 NodeName=Some name
-BaudRate=500
+Baudrate=500
 NetNumber=0
 LSS_SerialNumber=0