Bug fix for trying to load bad data using fom library: Encountered on loading keywords for article 01730

File "/usr/local/lib/python2.7/dist-packages/fom/mapping.py", line 438, in set_lazy_tag_value
    raise ValueError('Cannot lazy-save a non-primitive value.')
ValueError: Cannot lazy-save a non-primitive value.
Merge pull request #4 from gnott/tweaks

Bug fix for trying to load bad data using fom library: Encountered on lo...
Switch to using lxml xml parser instead of the html parser.
Merge pull request #5 from gnott/tweaks

Switch to using lxml xml parser instead of the html parser.