Call to prepare XML should be done only if data is present fixes #29

execute() should have data initialised with None
Hence, if no data is present, we should not call for preparation of XML
This would allow making calls like **GetTokenStatus**, which cannot be made with the current implementation.
update samples
Update __init__.py

bump trading version default to 837
add test
Merge branch 'master' of github.com:timotheus/ebaysdk-python
modify sample yaml file, add getOrders sample
modify sample yaml file, add getOrders sample
fix key issue when errors arg is not defined when using the SOAService class
ported to python3, multiple fixes
Merge branch 'master' of https://github.com/nderkach/ebaysdk-python
fix issues when running with python 2.7
add depracation warning when not using bs4
update deprecation text
rework type check
more py3 fixes
fix error handling bug
Merge pull request #36 from timotheus/nderkach-master

Nderkach master
test commit
Merge branch 'master' of github.com:timotheus/ebaysdk-python into nderkach-master
Merge pull request #37 from timotheus/nderkach-master

Nderkach master