fix tests
upgrade to lxml3 (element attributes are now sorted)
Merge pull request #144 from tomkralidis/master

upgrade to lxml3 (element attributes are now sorted)
bump dep versions
enhance unit tests for additional databases (#139)
oops, insert removed function
relax psycopg2 version requirement
Merge pull request #146 from tomkralidis/issue-139

enhance unit tests for additional databases (#139)
make harvesting suite optional
break harvesting tests into separate suite that is not tested by default
add config