Revert "Implement wbsetclaim function"

This reverts commit 227f0dddab5a3f6c5b87a101ae3a0e739210cc1b; backing
out due to broken build:

https://travis-ci.org/wikimedia/pywikibot-core/builds/10577053

Change-Id: I4eda408501751b19a848cf20e480c773df5f968c