Tag parse

Features included in this branch:
* Separate ``abstract`` and ``title`` CSV files in the settings required: look in example-settings.py for changes
* Lettuce tests
* Overflow CSV files allows for quotation marks to be allowed in ``abstract`` and ``title`` files content
* ``<i>`` tags are converted to ``<italic>`` tags, and &lt;sup&gt; and &lt;sub&gt; are also allowed tags

A set of recent CSV files will be provided for further testing of ``xml_generation.py``

Note: There may be an issue in production of additional whitespace in the abstract XML due to the XML pretty printing.
Note 2: When ready to deploy, the elife bot needs to be set to find and download abstract and title files and to be launched simultaneously.