Skip tests in the nice way

Related: d48160
cc @benlangfeld
Revert "Skip tests in the nice way"

This reverts commit 155c83dc476ae8c468d1fe90c37ac80dd9888186.

I was wrong @benlangfeld, apparently this is not the correct
way to skip a test.

@neonstalwart is there a cleaner way to skip a test?
Save memory by only defining these methods once
Merge pull request #286 from candy-chat/feature/save_memory

Save memory by only defining these methods once
Add basic test for requesting roster
This namespace is unnecessary, Strophe adds it
We can send a builder
Extract a test helper module
Create a main roster
Store roster items in main roster
Request our roster when we connect, before sending initial presence

According to http://xmpp.org/rfcs/rfc6121.html#roster-login