Update lxml to 3.1beta1.

Related to #199.
Running tests for all branches.
Merge branch 'lxml' into python3

Conflicts:
	setup.py
Merge branch 'lxml'
Update the zope.testbrowser docs.

It's need to instal the cssselector for zope.testbrowser works.
Closes #199.
Fixed a typo on docs.
Merge branch 'master' into python3